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javascript 打字与印刷页面代码_javascript技艺_脚本之

这里是要打印的内容 hello hello
hello hello hello
objc_getMetaClass
/** 
 * Returns the metaclass definition of a specified class.
 * 
 * @param name The name of the class to look up.
 * 
 * @return The c Class object for the metaclass of the named class, or c nil if the class
 *  is not registered with the Objective-C runtime.
 * 
 * @note If the definition for the named class is not registered, this function calls the class handler
 *  callback and then checks a second time to see if the class is registered. However, every class
 *  definition must have a valid metaclass definition, and so the metaclass definition is always returned,
 *  whether it’s valid or not.
 */
 // 得到一个类的元类
OBJC_EXPORT Class _Nullable
objc_getMetaClass(const char * _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Cat *cat1 = [[Cat alloc] init];
Class c1 = objc_getMetaClass("Cat");
NSLog(@"%@", c1);
NSLog(@"%@", cat1.name);

打印:

TestProject[25712:7077004] Cat
TestProject[25712:7077004] testH

用循环打印出多种三角形,循环打印三角形

打印一排*,很简单,打印下图

 www.5197.com 1

 

也很简单,代码如下: 

 1 public class Work10_3 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=0;
 9         while(a<4){
10             int i=0;
11             while(i<10){
12                 System.out.print("*");//打印*不换行
13                 i  ;
14             }
15             System.out.println("");//换行
16             a  ;
17         }
18     }
19 }

 

可是昨天想了好久都没想到怎样做到下面图片的样子,今天突然就有了灵感

www.5197.com 2

代码很简单,就是昨天想破了脑袋都想不出来,好笨啊我

第一行打印一个*,第二行行打印两个*,大三行打印三个*,这样分析就找到规律了,定义一个a=1,外层循环实现打印几行,定义一个i=0,

实现内层循环打印*,当a=1时是第一行,想让内层打印一个*,那么内层循环条件是i<1,这样就打印一个*,当a=2时,是第二行,想让内

层打印两个*,那么内层就是i<2,这样又不难看出i<a,于是代码如下:

 1 public class Work10 {
 2     /**
 3      * @param args
 4      */
 5     public static void main(String[] args) {
 6         // TODO Auto-generated method stub
 7         int a=1;
 8         while(a<25){
 9             int i=0;
10             while(i<a){
11                 System.out.print("*");//打印*不换行
12                 i  ;
13             }
14             System.out.println("");//换行
15             a  ;
16         }
17     }
18 }

 

很简单的代码,还可以改进一下。

有了一个灵感之后,就不能浪费,要充分锻炼自己的才能,

于是我又打印了一条斜线

www.5197.com 3

这是往右斜着的

 

让内层打印空格(和上面内层打印*一样),外层打印一个*,和刚才外层有些微小区别

代码如下:

 1 public class Work10_1 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=1;
 9         while(a<25){
10             int i=0;
11             while(i<a){
12                 System.out.print(" ");//打印空格不换行
13                 i  ;
14             }
15             System.out.print("*n");//打印*后换行
16             a  ;
17         }
18     }
19 
20 }

 

 www.5197.com 4

 

这是往左斜着的,内层我定义i=25,a=1时打印24个空格,然后打印*换行,当a=2时,打印23个空格,然后打印*换行。。。。。代码如下:

 

 1 public class Work10_2 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=1;
 9         while(a<25){
10             int i=25;
11             while(i>a){
12                 System.out.print(" ");//打印空格不换行
13                 i--;
14             }
15             System.out.print("*n");//打印*后换行
16             a  ;
17         }
18     }
19 
20 }

 

只有做不到的,没有想不到的,看下图

 www.5197.com 5

 

和上面一样的方法,一个内层while打印空格,另一个打印*,

这个也很简单,要是之前的我肯定不会这么说,现在知道怎么做了,就感觉简单了,

代码如下:

 

 1 public class Work10_4 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=1;
 9         while(a<25){
10             int i=25;
11             while(i>a){
12                 System.out.print(" ");//打印空格不换行
13                 i--;
14             }
15             int b=0;
16             while(b<a){
17                 System.out.print("*");//打印*不换行
18                 b  ;
19             }
20             System.out.println("");//换行
21             a  ;
22         }
23     }
24 
25 }

 

 

收回刚才的话啊 下面这个我没想到,就是改了下代码就变这样了,其实我想做一个等腰三角形的

 www.5197.com 6

 

代码如下:

 

 1 public class Work10_5 {
 2     public static void main(String[] args) {
 3         // TODO Auto-generated method stub
 4         int a=0;
 5         while(a<25){
 6             int i=25;
 7             while(i>a){
 8                 System.out.print(" ");//打印空格不换行
 9                 i--;
10             }
11             int b=0;
12             while(b<a){
13                 System.out.print("*");
14                 b =2;//这里和上面的不一样
15             }
16             System.out.println("");
17             a  ;
18         }
19     }
20 }

 

 

这个等腰三角形不好做啊 试了几次没有做出来,我要在定义一个变量试一试…

 

 

 

原来真是需要添加一个变量,添加以后瞬间就做出来了

 www.5197.com 7

 

分析一下,第一行先打印好多空格,然后一个*,第二行空格减少一个,*增加两个,因为增加的速度不一样,所以需要两个变量分别控制两个内层循环,空格的打印和之前的都一样, 只是打印*的速度要增加,代码如下:

 

 1         // TODO Auto-generated method stub
 2         int a=1;
 3         int c=1;
 4         while(a<25){
 5             int i=25;
 6             while(i>a){
 7                 System.out.print(" ");
 8                 i--;
 9             }
10             int b=0;
11             while(b<c){
12                 System.out.print("*");
13                 b  ;
14             }
15             System.out.println("");
16             a  ;
17             c =2;
18         }
19     

 

然后我又想打印一个倒三角,然后很轻松就打印出来了

 www.5197.com 8

 

这个就不多说了,代码如下:

 

 1 public class Work10_6 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=1;
 9         int c=1;
10         while(a<25){
11             int i=25;
12             while(i>a){
13                 System.out.print(" ");
14                 i--;
15             }
16             int b=0;
17             while(b<c){
18                 System.out.print("*");
19                 b  ;
20             }
21             System.out.println("");
22             a  ;
23             c =2;
24         }
25     }
26 
27 }

 还能把这写三角形组合起来,有多种组合方式,下面提供一种做参考:

www.5197.com 9

代码如下:

 

 1 public class Work10_13 {
 2 
 3     /**
 4      * @param args
 5      */
 6     public static void main(String[] args) {
 7         // TODO Auto-generated method stub
 8         int a=1;
 9         int c=1;
10         while(a<20){
11             int i=20;
12             while(i>a){
13                 System.out.print(" ");
14                 i--;
15             }
16             int b=0;
17             while(b<c){
18                 System.out.print("*");
19                 b  ;
20             }
21             System.out.println("");
22             a  ;
23             c =2;
24         }
25         int d=0;
26         int e=39;
27         while(d<20){
28             int i=0;
29             while(i<d){
30                 System.out.print(" ");//打印空格不换行
31                 i  ;
32             }
33             int b=0;
34             while(b<e){ 
35                 System.out.print("*");
36                 b  ;
37             }
38             System.out.println("");
39             d  ;
40             e-=2;
41         }
42     }
43 }

转载请注明出处!

打印一排*,很简单,打印下图 也很简单,代码如下: 1 public class Work10_3 { 2 3 /** 4 * @param args...

设置标题

protocol_isEqual

/** 
 * Returns a Boolean value that indicates whether two protocols are equal.
 * 
 * @param proto A protocol.
 * @param other A protocol.
 * 
 * @return c YES if e proto is the same as e other, otherwise c NO.
 */
 // 判断两个协议是否相等
OBJC_EXPORT BOOL
protocol_isEqual(Protocol * _Nullable proto, Protocol * _Nullable other)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("UITableViewDataSource");
Protocol *protocolB = NSProtocolFromString(@"UITableViewDataSource");
BOOL isEqual = protocol_isEqual(protocolA, protocolB);

打印:

(lldb) po isEqual
YES

javascript打印页面

objc_removeAssociatedObjects

/** 
 * Removes all associations for a given object.
 * 
 * @param object An object that maintains associated objects.
 * 
 * @note The main purpose of this function is to make it easy to return an object 
 *  to a "pristine state”. You should not use this function for general removal of
 *  associations from objects, since it also removes associations that other clients
 *  may have added to the object. Typically you should use c objc_setAssociatedObject 
 *  with a nil value to clear an association.
 * 
 * @see objc_setAssociatedObject
 * @see objc_getAssociatedObject
 */
 // 删除给定对象的所有的关联
OBJC_EXPORT void
objc_removeAssociatedObjects(id _Nonnull object)
    OBJC_AVAILABLE(10.6, 3.1, 9.0, 1.0, 2.0);

打印

class_getMethodImplementation_stret

/** 
 * Returns the function pointer that would be called if a particular 
 * message were sent to an instance of a class.
 * 
 * @param cls The class you want to inspect.
 * @param name A selector.
 * 
 * @return The function pointer that would be called if c [object name] were called
 *  with an instance of the class, or c NULL if e cls is c Nil.
 */
 // 返回方法的具体的实现
OBJC_EXPORT IMP _Nullable
class_getMethodImplementation_stret(Class _Nullable cls, SEL _Nonnull name) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARM64_UNAVAILABLE;

代码:

打印:

复制代码 代码如下:

property_getAttributes

/** 
 * Returns the attribute string of a property.
 * 
 * @param property A property.
 *
 * @return A C string containing the property's attributes.
 * 
 * @note The format of the attribute string is described in Declared Properties in Objective-C Runtime Programming Guide.
 */
 // 返回属性的属性字符串
OBJC_EXPORT const char * _Nullable
property_getAttributes(objc_property_t _Nonnull property) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

id lenderClass = objc_getClass("Person");
unsigned int outCount, I;
objc_property_t *properties = class_copyPropertyList(lenderClass, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    objc_property_t property = properties[I];
    fprintf(stdout, "%s %sn", property_getName(property), property_getAttributes(property));
}

打印:

manTest T@"NSString",&,N,V_manTest
age Tq,N,V_age

打印解释:

www.5197.com 10

image

property_copyAttributeList

/** 
 * Returns an array of property attributes for a property. 
 * 
 * @param property The property whose attributes you want copied.
 * @param outCount The number of attributes returned in the array.
 * 
 * @return An array of property attributes; must be free'd() by the caller. 
 */
 // 返回属性的属性列表值
OBJC_EXPORT objc_property_attribute_t * _Nullable
property_copyAttributeList(objc_property_t _Nonnull property,
                           unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

id lenderClass = objc_getClass("Person");
unsigned int outCount;
objc_property_t *properties = class_copyPropertyList(lenderClass, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    objc_property_t property = properties[I];
    fprintf(stdout, "%s %sn", property_getName(property), property_getAttributes(property));

    unsigned int attrCount = 0;
    objc_property_attribute_t *attrs = property_copyAttributeList(property, &attrCount);
    for (unsigned int j = 0; j < attrCount; j  ) {
        objc_property_attribute_t attr = attrs[j];
        const char *name = attr.name;
        const char *value = attr.value;
        NSLog(@"属性的描述: %s 值: %s", name, value);
    }
}

打印:

manTest T@"NSString",&,N,V_manTest
TestProject[23001:481165] 属性的描述: T 值: @"NSString"
TestProject[23001:481165] 属性的描述: & 值: 
TestProject[23001:481165] 属性的描述: N 值: 
TestProject[23001:481165] 属性的描述: V 值: _manTest

age Tq,N,V_age
TestProject[23001:481165] 属性的描述: T 值: q
TestProject[23001:481165] 属性的描述: N 值: 
TestProject[23001:481165] 属性的描述: V 值: _age

class_getInstanceMethod

/** 
 * Returns a specified instance method for a given class.
 * 
 * @param cls The class you want to inspect.
 * @param name The selector of the method you want to retrieve.
 * 
 * @return The method that corresponds to the implementation of the selector specified by 
 *  e name for the class specified by e cls, or c NULL if the specified class or its 
 *  superclasses do not contain an instance method with the specified selector.
 *
 * @note This function searches superclasses for implementations, whereas c class_copyMethodList does not.
 */
 // 获取类的实例化方法
OBJC_EXPORT Method _Nullable
class_getInstanceMethod(Class _Nullable cls, SEL _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Method methodI = class_getInstanceMethod([self class], @selector(viewWillAppear:));

打印:

(lldb) po methodI
0x000000010ca31528

SEL

Ivar

定义

/// An opaque type that represents a category.
typedef struct objc_category *Category;

IMP

/// A pointer to the function of a method implementation. 
#if !OBJC_OLD_DISPATCH_PROTOTYPES
typedef void (*IMP)(void /* id, SEL, ... */ ); 
#else
typedef id _Nullable (*IMP)(id _Nonnull, SEL _Nonnull, ...); 
#endif

IMP 指针指向方法的具体的实现

class_isMetaClass
/** 
 * Returns a Boolean value that indicates whether a class object is a metaclass.
 * 
 * @param cls A class object.
 * 
 * @return c YES if e cls is a metaclass, c NO if e cls is a non-meta class, 
 *  c NO if e cls is c Nil.
 */
 // 判断输出的类是否为元类
OBJC_EXPORT BOOL
class_isMetaClass(Class _Nullable cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

if (class_isMetaClass(objc_getMetaClass("Cat"))) {
    NSLog(@"YES");
}

打印:

TestProject[41512:7792603] YES
object_getInstanceVariable
/** 
 * Obtains the value of an instance variable of a class instance.
 * 
 * @param obj A pointer to an instance of a class. Pass the object containing
 *  the instance variable whose value you wish to obtain.
 * @param name A C string. Pass the name of the instance variable whose value you wish to obtain.
 * @param outValue On return, contains a pointer to the value of the instance variable.
 * 
 * @return A pointer to the c Ivar data structure that defines the type and name of
 *  the instance variable specified by e name.
 */
 // 获取实例变量的值 MRC 环境下有用
OBJC_EXPORT Ivar _Nullable
object_getInstanceVariable(id _Nullable obj, const char * _Nonnull name,
                           void * _Nullable * _Nullable outValue)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = object_getInstanceVariable(p1, "_manTest", nil);
NSLog(@" --- %@", object_getIvar(p1, ivar));

打印:

TestProject[22787:6839305]  --- chen test

Protocol

定义:

typedef struct objc_object Protocol;

class_getClassVariable
/** 
 * Returns the Ivar for a specified class variable of a given class.
 * 
 * @param cls The class definition whose class variable you wish to obtain.
 * @param name The name of the class variable definition to obtain.
 * 
 * @return A pointer to an c Ivar data structure containing information about the class variable specified by e name.
 */
 // 获取参数 cls 类的变量名为name的变量

OBJC_EXPORT Ivar _Nullable
class_getClassVariable(Class _Nullable cls, const char * _Nonnull name) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Ivar viewIvar = class_getClassVariable([UIView class], "isa");
id getViewIvar = object_getIvar([UIView class], viewIvar);
NSLog(@"%d", class_isMetaClass(getViewIvar));
NSLog(@"%@", getViewIvar);

打印:

TestProject[42676:7900606] 1
TestProject[42676:7900606] UIView
object_setIvar
/** 
 * Sets the value of an instance variable in an object.
 * 
 * @param obj The object containing the instance variable whose value you want to set.
 * @param ivar The Ivar describing the instance variable whose value you want to set.
 * @param value The new value for the instance variable.
 * 
 * @note Instance variables with known memory management (such as ARC strong and weak)
 *  use that memory management. Instance variables with unknown memory management 
 *  are assigned as if they were unsafe_unretained.
 * @note c object_setIvar is faster than c object_setInstanceVariable if the Ivar
 *  for the instance variable is already known.
 */
 // 可以给私有变量设置值 速度超过 object_setInstanceVariable
OBJC_EXPORT void
object_setIvar(id _Nullable obj, Ivar _Nonnull ivar, id _Nullable value) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");
object_setIvar(p1, ivar, @"shuaibi");
定义
/// An opaque type that represents an instance variable.
typedef struct objc_ivar *Ivar;

protocol_addProperty

/** 
 * Adds a property to a protocol. The protocol must be under construction. 
 * 
 * @param proto The protocol to add a property to.
 * @param name The name of the property.
 * @param attributes An array of property attributes.
 * @param attributeCount The number of attributes in e attributes.
 * @param isRequiredProperty YES if the property (accessor methods) is not optional. 
 * @param isInstanceProperty YES if the property (accessor methods) are instance methods. 
 *  This is the only case allowed fo a property, as a result, setting this to NO will 
 *  not add the property to the protocol at all. 
 */
 //
OBJC_EXPORT void
protocol_addProperty(Protocol * _Nonnull proto, const char * _Nonnull name,
                     const objc_property_attribute_t * _Nullable attributes,
                     unsigned int attributeCount,
                     BOOL isRequiredProperty, BOOL isInstanceProperty)
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

    // 创建新的协议
    Protocol *newProtocol = objc_allocateProtocol("DataDelegate");

    // 给一个协议添加一个属性
    objc_property_attribute_t attr_T = {"T", "@"NSString""};   // @encod
    objc_property_attribute_t attr_N = {"N", ""};  // 原子性
    objc_property_attribute_t attr_C = {"C", ""};  // copy
    objc_property_attribute_t attr_V = {"V", "_age"}; // 实例变量
    objc_property_attribute_t attrs[] = {attr_T, attr_N, attr_C, attr_V};
    protocol_addProperty(newProtocol, "age", attrs, 4, YES, YES);

    // 打印协议的属性
    unsigned int outCount;
    objc_property_t *propertyList = protocol_copyPropertyList(newProtocol, &outCount);
    for (unsigned int i = 0; i < outCount; i  ) {
        objc_property_t property = propertyList[I];
        unsigned propertyCount;
        objc_property_attribute_t *attrList = property_copyAttributeList(property, &propertyCount);
        for (unsigned int j  = 0; j < propertyCount; j  ) {
            objc_property_attribute_t attr = attrList[j];
            const char *name = attr.name;
            const char *value = attr.value;
            NSLog(@"name: %s, value: %s", name, value);
        }
    }

打印:

TestProject[33846:1268389] name: T, value: @"NSString"
TestProject[33846:1268389] name: N, value: 
TestProject[33846:1268389] name: C, value: 
TestProject[33846:1268389] name: V, value: _age

method_exchangeImplementations

Method method1 = class_getInstanceMethod([NSString class], @selector(lowercaseString));
Method method2 = class_getInstanceMethod([NSString class], @selector(uppercaseString));
method_exchangeImplementations(method1, method2);//交换两个方法后,两个方法的功能相反

class_getIvarLayout

/** 
 * Returns a description of the c Ivar layout for a given class.
 * 
 * @param cls The class to inspect.
 * 
 * @return A description of the c Ivar layout for e cls.
 */
 // 返回一个类的修饰属性
OBJC_EXPORT const uint8_t * _Nullable
class_getIvarLayout(Class _Nullable cls)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

const uint8_t *array_s = class_getIvarLayout([Person class]);

打印:

(lldb) po array_s
"x01"
结构
struct objc_ivar {
    char * _Nullable ivar_name                               OBJC2_UNAVAILABLE;
    char * _Nullable ivar_type                               OBJC2_UNAVAILABLE;
    int ivar_offset                                          OBJC2_UNAVAILABLE;
#ifdef __LP64__
    int space                                                OBJC2_UNAVAILABLE;
#endif
}

objc_copyProtocolList

/** 
 * Returns an array of all the protocols known to the runtime.
 * 
 * @param outCount Upon return, contains the number of protocols in the returned array.
 * 
 * @return A C array of all the protocols known to the runtime. The array contains c *outCount
 *  pointers followed by a c NULL terminator. You must free the list with c free().
 * 
 * @note This function acquires the runtime lock.
 */
 // 返回运行时系统所有的协议
OBJC_EXPORT Protocol * __unsafe_unretained _Nonnull * _Nullable
objc_copyProtocolList(unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int outCount;
Protocol **protocolList = objc_copyProtocolList(&outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    Protocol *protocol = protocolList[I];
    NSLog(@"%s", protocol_getName(protocol));
}

打印:

TestProject[23401:517412] UIVideoEditorControllerDelegate
TestProject[23401:517412] _UIIVCResponseDelegate
TestProject[23401:517412] _UITouchable
TestProject[23401:517412] WebOpenPanelResultListener
TestProject[23401:517412] SBSRemoteAlertClientHandle
TestProject[23401:517412] _UIContentContainerInternal
TestProject[23401:517412] _UIKeyboardAutoRespondingScrollView
TestProject[23401:517412] CAMLWriterDelegate
TestProject[23401:517412] OS_nw_endpoint_resolver
TestProject[23401:517412] _UIActivityHelperDelegate

定义

/// An opaque type that represents an Objective-C declared property.
typedef struct objc_property *objc_property_t;
sel_registerName
/** 
 * Registers a method with the Objective-C runtime system, maps the method 
 * name to a selector, and returns the selector value.
 * 
 * @param str A pointer to a C string. Pass the name of the method you wish to register.
 * 
 * @return A pointer of type SEL specifying the selector for the named method.
 * 
 * @note You must register a method name with the Objective-C runtime system to obtain the
 *  method’s selector before you can add the method to a class definition. If the method name
 *  has already been registered, this function simply returns the selector.
 */

// 注册一个方法,对这个runtime系统返回一个SEL,如果这个方法的名字早已经被注册,那么这个函数只会返回 SEL
OBJC_EXPORT SEL _Nonnull sel_registerName(const char * _Nonnull str)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

((void (*)(id, SEL))(void *)objc_msgSend)((id)self, sel_registerName("testFormat"));

打印:

TestProject[22427:6817642] testFormat

objc_property_attribute_t

结构:

/// Defines a property attribute
typedef struct {
    const char * _Nonnull name;           /**< The name of the attribute */
    const char * _Nonnull value;          /**< The value of the attribute (usually empty) */
} objc_property_attribute_t;

结构

struct objc_category {
    // 分类名字
    char * _Nonnull category_name                            OBJC2_UNAVAILABLE;
    // 类名
    char * _Nonnull class_name                               OBJC2_UNAVAILABLE;
    // objc 实例方法列表
    struct objc_method_list * _Nullable instance_methods     OBJC2_UNAVAILABLE;
    // objc 类方法列表
    struct objc_method_list * _Nullable class_methods        OBJC2_UNAVAILABLE;
    // 协议列表
    struct objc_protocol_list * _Nullable protocols          OBJC2_UNAVAILABLE;
}                                                            OBJC2_UNAVAILABLE;
object_isClass
/** 
 * Returns whether an object is a class object.
 * 
 * @param obj An Objective-C object.
 * 
 * @return true if the object is a class or metaclass, false otherwise.
 */
 // 判断是否是一个不为空的类对象
OBJC_EXPORT BOOL
object_isClass(id _Nullable obj)
    OBJC_AVAILABLE(10.10, 8.0, 9.0, 1.0, 2.0);

代码:

BOOL isp1 = object_isClass([p1 class]);
Person * p2;
BOOL isp2 = object_isClass([p2 class]);
NSString * p3 = @"test";
BOOL isp3 = object_isClass([p3 class]);
NSLog(@"%i", isp1);
NSLog(@"%i", isp2);
NSLog(@"%i", isp3);

打印:

TestProject[24619:6998034] 1
TestProject[24619:6998034] 0
TestProject[24619:6998034] 1

class_getImageName

/** 
 * Returns the dynamic library name a class originated from.
 * 
 * @param cls The class you are inquiring about.
 * 
 * @return The name of the library containing this class.
 */
 // 返回这个类 源动态库名称
OBJC_EXPORT const char * _Nullable
class_getImageName(Class _Nullable cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

const char *libraryName = class_getImageName([UIViewController class]);
NSLog(@"name: %s", libraryName);

打印:

TestProject[34267:1284976] name: /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/UIKit.framework/UIKit

class_getWeakIvarLayout

/** 
 * Returns a description of the layout of weak Ivars for a given class.
 * 
 * @param cls The class to inspect.
 * 
 * @return A description of the layout of the weak c Ivars for e cls.
 */
 //  待续
OBJC_EXPORT const uint8_t * _Nullable
class_getWeakIvarLayout(Class _Nullable cls)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

打印:

class_setVersion
/** 
 * Sets the version number of a class definition.
 * 
 * @param cls A pointer to an Class data structure. 
 *  Pass the class definition for which you wish to set the version.
 * @param version An integer. Pass the new version number of the class definition.
 *
 * @note You can use the version number of the class definition to provide versioning of the
 *  interface that your class represents to other classes. This is especially useful for object
 *  serialization (that is, archiving of the object in a flattened form), where it is important to
 *  recognize changes to the layout of the instance variables in different class-definition versions.
 * @note Classes derived from the Foundation framework c NSObject class can set the class-definition
 *  version number using the c setVersion: class method, which is implemented using the c class_setVersion function.
 */
 // 设置类的版本号
OBJC_EXPORT void
class_setVersion(Class _Nullable cls, int version)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"%d", class_getVersion([self class]));
class_setVersion([self class], 2);
NSLog(@"%d", class_getVersion([self class]));

版本:

TestProject[42247:7871127] 0
TestProject[42247:7871127] 2

Runtime

ivar_getOffset
/** 
 * Returns the offset of an instance variable.
 * 
 * @param v The instance variable you want to enquire about.
 * 
 * @return The offset of e v.
 * 
 * @note For instance variables of type c id or other object types, call c object_getIvar
 *  and c object_setIvar instead of using this offset to access the instance variable data directly.
 */
 // 得到实例变量的偏移量
OBJC_EXPORT ptrdiff_t
ivar_getOffset(Ivar _Nonnull v) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = object_getInstanceVariable(p1, "_manTest", nil);
NSLog(@"%ld", ivar_getOffset(ivar));

打印:

TestProject[23488:6907490] 8
class_getInstanceVariable
/** 
 * Returns the c Ivar for a specified instance variable of a given class.
 * 
 * @param cls The class whose instance variable you wish to obtain.
 * @param name The name of the instance variable definition to obtain.
 * 
 * @return A pointer to an c Ivar data structure containing information about 
 *  the instance variable specified by e name.
 */
OBJC_EXPORT Ivar _Nullable
class_getInstanceVariable(Class _Nullable cls, const char * _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");

打印:

(lldb) po ivar
0x00000001098a1460
object_setClass
/** 
 * Sets the class of an object.
 * 
 * @param obj The object to modify.
 * @param cls A class object.
 * 
 * @return The previous value of e object's class, or c Nil if e object is c nil.
 */
OBJC_EXPORT Class _Nullable
object_setClass(id _Nullable obj, Class _Nonnull cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
NSLog(@"n p1 = %@", p1);
Class c1 = object_setClass(p1, [Cat class]);
NSLog(@"n c1 = %@ n p1 = %@", c1, p1);

打印:

TestProject[24490:6987169] 
 p1 = <Person: 0x60000000a580>
TestProject[24490:6987169] 
 c1 = Person 
 p1 = <Cat: 0x60000000a580>

class_conformsToProtocol

/** 
 * Returns a Boolean value that indicates whether a class conforms to a given protocol.
 * 
 * @param cls The class you want to inspect.
 * @param protocol A protocol.
 *
 * @return YES if cls conforms to protocol, otherwise NO.
 *
 * @note You should usually use NSObject's conformsToProtocol: method instead of this function.
 */
// 返回一个 Boolean 值,检查某个类是否遵从某个协议
OBJC_EXPORT BOOL
class_conformsToProtocol(Class _Nullable cls, Protocol * _Nullable protocol) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocol = NSProtocolFromString(@"UITableViewDataSource");
BOOL isConforms = class_conformsToProtocol([UITableViewController class], protocol);

打印:

(lldb) po isConforms
YES

class_getClassMethod

/** 
 * Returns a pointer to the data structure describing a given class method for a given class.
 * 
 * @param cls A pointer to a class definition. Pass the class that contains the method you want to retrieve.
 * @param name A pointer of type c SEL. Pass the selector of the method you want to retrieve.
 * 
 * @return A pointer to the c Method data structure that corresponds to the implementation of the 
 *  selector specified by aSelector for the class specified by aClass, or NULL if the specified 
 *  class or its superclasses do not contain an instance method with the specified selector.
 *
 * @note Note that this function searches superclasses for implementations, 
 *  whereas c class_copyMethodList does not.
 */
 // 获取类方法
OBJC_EXPORT Method _Nullable
class_getClassMethod(Class _Nullable cls, SEL _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Method method = class_getClassMethod([Person class], @selector(test));

打印:

(lldb) po method
0x0000000106c633d8
object_setInstanceVariableWithStrongDefault
/** 
 * Changes the value of an instance variable of a class instance.
 * 
 * @param obj A pointer to an instance of a class. Pass the object containing
 *  the instance variable whose value you wish to modify.
 * @param name A C string. Pass the name of the instance variable whose value you wish to modify.
 * @param value The new value for the instance variable.
 * 
 * @return A pointer to the c Ivar data structure that defines the type and 
 *  name of the instance variable specified by e name.
 *
 * @note Instance variables with known memory management (such as ARC strong and weak)
 *  use that memory management. Instance variables with unknown memory management 
 *  are assigned as if they were strong.
 */
 // 在MRC环境下使用,更改实例的实例变量的值
OBJC_EXPORT Ivar _Nullable
object_setInstanceVariableWithStrongDefault(id _Nullable obj,
                                            const char * _Nonnull name,
                                            void * _Nullable value)
    OBJC_AVAILABLE(10.12, 10.0, 10.0, 3.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");
if (@available(iOS 10.0, *)) {
    object_setInstanceVariableWithStrongDefault(p1, "_manTest", @"shuaibi");
} else {
        // Fallback on earlier versions
}
object_setIvarWithStrongDefault
/** 
 * Sets the value of an instance variable in an object.
 * 
 * @param obj The object containing the instance variable whose value you want to set.
 * @param ivar The Ivar describing the instance variable whose value you want to set.
 * @param value The new value for the instance variable.
 * 
 * @note Instance variables with known memory management (such as ARC strong and weak)
 *  use that memory management. Instance variables with unknown memory management 
 *  are assigned as if they were strong.
 * @note c object_setIvar is faster than c object_setInstanceVariable if the Ivar
 *  for the instance variable is already known.
 */
 // 设置变量中实例变量的值 / iOS 10.0 
OBJC_EXPORT void
object_setIvarWithStrongDefault(id _Nullable obj, Ivar _Nonnull ivar,
                                id _Nullable value) 
    OBJC_AVAILABLE(10.12, 10.0, 10.0, 3.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");
if (@available(iOS 10.0, *)) {
    object_setIvarWithStrongDefault(p1, ivar, @"chen123");
} else {
    // Fallback on earlier versions
}

objc_method_description

结构:

/// Defines a method
struct objc_method_description {
    SEL _Nullable name;               /**< The name of the method */
    char * _Nullable types;           /**< The types of the method arguments */
};

class_copyMethodList

/** 
 * Describes the instance methods implemented by a class.
 * 
 * @param cls The class you want to inspect.
 * @param outCount On return, contains the length of the returned array. 
 *  If outCount is NULL, the length is not returned.
 * 
 * @return An array of pointers of type Method describing the instance methods 
 *  implemented by the class—any instance methods implemented by superclasses are not included. 
 *  The array contains *outCount pointers followed by a NULL terminator. You must free the array with free().
 * 
 *  If cls implements no instance methods, or cls is Nil, returns NULL and *outCount is 0.
 * 
 * @note To get the class methods of a class, use c class_copyMethodList(object_getClass(cls), &count).
 * @note To get the implementations of methods that may be implemented by superclasses, 
 *  use c class_getInstanceMethod or c class_getClassMethod.
 */
 // 得到类的方法列表
OBJC_EXPORT Method _Nonnull * _Nullable
class_copyMethodList(Class _Nullable cls, unsigned int * _Nullable outCount) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int count;
Method *methodList = class_copyMethodList([self class], &count);
for (unsigned int i = 0; i < count; i  ) {
    Method method = methodList[I];
    NSLog(@"%s", sel_getName(method_getName(method)));
}

打印:

TestProject[44285:8024690] testFormat
TestProject[44285:8024690] didReceiveMe
TestProject[44285:8024690] viewDidLoad
objc_copyClassList
/** 
 * Creates and returns a list of pointers to all registered class definitions.
 * 
 * @param outCount An integer pointer used to store the number of classes returned by
 *  this function in the list. It can be c nil.
 * 
 * @return A nil terminated array of classes. It must be freed with c free().
 * 
 * @see objc_getClassList
 */
 // 获取所有已经注册的类
OBJC_EXPORT Class _Nonnull * _Nullable
objc_copyClassList(unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.7, 3.1, 9.0, 1.0, 2.0);

代码:

unsigned int outCount;
Class *classes = objc_copyClassList(&outCount);
for (int i = 0; i < outCount; i  ) {
    NSLog(@"%s", class_getName(classes[i]));
}

打印:

TestProject[41322:7782252] JSExport
TestProject[41322:7782252] NSLeafProxy
TestProject[41322:7782252] NSProxy
TestProject[41322:7782252] _UITargetedProxy
TestProject[41322:7782252] _UIViewServiceReplyControlTrampoline

Category

class_copyPropertyList

/** 
 * Describes the properties declared by a class.
 * 
 * @param cls The class you want to inspect.
 * @param outCount On return, contains the length of the returned array. 
 *  If e outCount is c NULL, the length is not returned.        
 * 
 * @return An array of pointers of type c objc_property_t describing the properties 
 *  declared by the class. Any properties declared by superclasses are not included. 
 *  The array contains c *outCount pointers followed by a c NULL terminator. You must free the array with c free().
 * 
 *  If e cls declares no properties, or e cls is c Nil, returns c NULL and c *outCount is c 0.
 */
 // 得到类属性列表
OBJC_EXPORT objc_property_t _Nonnull * _Nullable
class_copyPropertyList(Class _Nullable cls, unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int propertyCount;
objc_property_t *propertyList = class_copyPropertyList([Person class], &propertyCount);
for (unsigned int i = 0; i < propertyCount; i  ) {
    objc_property_t property_t = propertyList[I];
    NSLog(@"%s", property_getName(property_t));
}
free(propertyList);

打印:

TestProject[20198:223479] manTest
TestProject[20198:223479] age

protocol_getMethodDescription

/** 
 * Returns a method description structure for a specified method of a given protocol.
 * 
 * @param p A protocol.
 * @param aSel A selector.
 * @param isRequiredMethod A Boolean value that indicates whether aSel is a required method.
 * @param isInstanceMethod A Boolean value that indicates whether aSel is an instance method.
 * 
 * @return An c objc_method_description structure that describes the method specified by e aSel,
 *  e isRequiredMethod, and e isInstanceMethod for the protocol e p.
 *  If the protocol does not contain the specified method, returns an c objc_method_description structure
 *  with the value c {NULL, c NULL}.
 * 
 * @note This function recursively searches any protocols that this protocol conforms to.
 */
 // 返回协议中指定方法的描述
OBJC_EXPORT struct objc_method_description
protocol_getMethodDescription(Protocol * _Nonnull proto, SEL _Nonnull aSel,
                              BOOL isRequiredMethod, BOOL isInstanceMethod)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

struct objc_method_description desc = protocol_getMethodDescription(protocolA, @selector(numberOfSectionsInTableView:), NO, YES);

打印:

(lldb) po desc.name
"numberOfSectionsInTableView:"

(lldb) po desc.types
"q24@0:8@16"
objc_getClass
/* Obtaining Class Definitions */

/** 
 * Returns the class definition of a specified class.
 * 
 * @param name The name of the class to look up.
 * 
 * @return The Class object for the named class, or c nil
 *  if the class is not registered with the Objective-C runtime.
 * 
 * @note c objc_getClass is different from c objc_lookUpClass in that if the class
 *  is not registered, c objc_getClass calls the class handler callback and then checks
 *  a second time to see whether the class is registered. c objc_lookUpClass does 
 *  not call the class handler callback.
 * 
 * @warning Earlier implementations of this function (prior to OS X v10.0)
 *  terminate the program if the class does not exist.
 */
OBJC_EXPORT Class _Nullable
objc_getClass(const char * _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Cat *cat1 = [[Cat alloc] init];
Class c1 = object_getClass(cat1);
NSLog(@"%@", c1);
NSLog(@"%@", cat1.name);

打印:

TestProject[24927:7020395] Cat
TestProject[24927:7020395] testH
定义
/// An opaque type that represents a method in a class definition.
typedef struct objc_method *Method;

Class

ivar_getName
/* Working with Instance Variables */

/** 
 * Returns the name of an instance variable.
 * 
 * @param v The instance variable you want to enquire about.
 * 
 * @return A C string containing the instance variable's name.
 */

 // 返回实时变量的名称

OBJC_EXPORT const char * _Nullable
ivar_getName(Ivar _Nonnull v) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = object_getInstanceVariable(p1, "_manTest", nil);
NSLog(@"%s", ivar_getName(ivar));

打印:

TestProject[22909:6849954] _manTest
sel_getName
/// Returns the name of the method specified by a given selector.
// 通过 SEL 返回方法名字
OBJC_EXPORT const char * _Nonnull sel_getName(SEL _Nonnull sel)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"--- %s", sel_getName(@selector(testFormat)));

打印:

TestProject[22016:6798169] --- testFormat

objc_registerProtocol

/** 
 * Registers a newly constructed protocol with the runtime. The protocol
 * will be ready for use and is immutable after this.
 * 
 * @param proto The protocol you want to register.
 */
 // 注册协议
OBJC_EXPORT void
objc_registerProtocol(Protocol * _Nonnull proto) 
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

Protocol *protocol = objc_allocateProtocol("PersonDelegate");
// 声明这个协议还是不可以用的,还是要注册这个协议的
objc_registerProtocol(protocol);

打印:

(lldb) po protocol
<Protocol: 0x6080000a84c0>

property_getName

/* Working with Properties */

/** 
 * Returns the name of a property.
 * 
 * @param property The property you want to inquire about.
 * 
 * @return A C string containing the property's name.
 */
 // 返回属性的名字
OBJC_EXPORT const char * _Nonnull
property_getName(objc_property_t _Nonnull property) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

objc_property_t property_t = class_getProperty([Person class], "age");
const char *name = property_getName(property_t);
NSLog(@"%s", name);

打印:

TestProject[21844:408300] age
class_getSuperclass
/** 
 * Returns the superclass of a class.
 * 
 * @param cls A class object.
 * 
 * @return The superclass of the class, or c Nil if
 *  e cls is a root class, or c Nil if e cls is c Nil.
 *
 * @note You should usually use c NSObject's c superclass method instead of this function.
 */
 // 得到这个类的父类
OBJC_EXPORT Class _Nullable
class_getSuperclass(Class _Nullable cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"%@", class_getSuperclass([self class]));

打印:

TestProject[41571:7797664] UIViewController
objc_lookUpClass
/** 
 * Returns the class definition of a specified class.
 * 
 * @param name The name of the class to look up.
 * 
 * @return The Class object for the named class, or c nil if the class
 *  is not registered with the Objective-C runtime.
 * 
 * @note c objc_getClass is different from this function in that if the class is not
 *  registered, c objc_getClass calls the class handler callback and then checks a second
 *  time to see whether the class is registered. This function does not call the class handler callback.
 */
 // 获取指定的类,如果没有注册则返回 nil
OBJC_EXPORT Class _Nullable
objc_lookUpClass(const char * _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Class cl1 = objc_lookUpClass("Ca");
Class cl2 = objc_lookUpClass("Cat");
class_getVersion
/** 
 * Returns the version number of a class definition.
 * 
 * @param cls A pointer to a c Class data structure. Pass
 *  the class definition for which you wish to obtain the version.
 * 
 * @return An integer indicating the version number of the class definition.
 *
 * @see class_setVersion
 */
 // 获取类的版本号  待续...
OBJC_EXPORT int
class_getVersion(Class _Nullable cls)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"%d", class_getVersion([self class]));

打印:

TestProject[42051:7849333] 0

Method

class_getMethodImplementation

/** 
 * Returns the function pointer that would be called if a 
 * particular message were sent to an instance of a class.
 * 
 * @param cls The class you want to inspect.
 * @param name A selector.
 * 
 * @return The function pointer that would be called if c [object name] were called
 *  with an instance of the class, or c NULL if e cls is c Nil.
 *
 * @note c class_getMethodImplementation may be faster than c method_getImplementation(class_getInstanceMethod(cls, name)).
 * @note The function pointer returned may be a function internal to the runtime instead of
 *  an actual method implementation. For example, if instances of the class do not respond to
 *  the selector, the function pointer returned will be part of the runtime's message forwarding machinery.
 */
 // 得到指向方法实现的指针
OBJC_EXPORT IMP _Nullable
class_getMethodImplementation(Class _Nullable cls, SEL _Nonnull name) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

IMP imp = class_getMethodImplementation([self class], @selector(viewWillAppear:));

打印:

(lldb) po imp
(UIKit`-[UIViewController viewWillAppear:])

objc_getAssociatedObject

/** 
 * Returns the value associated with a given object for a given key.
 * 
 * @param object The source object for the association.
 * @param key The key for the association.
 * 
 * @return The value associated with the key e key for e object.
 * 
 * @see objc_setAssociatedObject
 */
 // 通过对象和 key 得到一个关联值
OBJC_EXPORT id _Nullable
objc_getAssociatedObject(id _Nonnull object, const void * _Nonnull key)
    OBJC_AVAILABLE(10.6, 3.1, 9.0, 1.0, 2.0);

protocol_copyProtocolList

/** 
 * Returns an array of the protocols adopted by a protocol.
 * 
 * @param proto A protocol.
 * @param outCount Upon return, contains the number of elements in the returned array.
 * 
 * @return A C array of protocols adopted by e proto. The array contains e *outCount pointers
 *  followed by a c NULL terminator. You must free the array with c free().
 *  If the protocol declares no properties, c NULL is returned and c *outCount is c 0.
 */
 // 返回协议所遵守的协议,以数组的形式展现
OBJC_EXPORT Protocol * __unsafe_unretained _Nonnull * _Nullable
protocol_copyProtocolList(Protocol * _Nonnull proto,
                          unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("CatDelegate");
unsigned int outCount;
Protocol **protocolList = protocol_copyProtocolList(protocolA, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    Protocol *protocol = protocolList[I];
    NSLog(@"name --- %s", protocol_getName(protocol));
}

打印:

TestProject[26997:828030] name --- NSObject

结构

struct objc_class {
    Class _Nonnull isa  OBJC_ISA_AVAILABILITY;

#if !__OBJC2__
    Class _Nullable super_class                              OBJC2_UNAVAILABLE;
    const char * _Nonnull name                               OBJC2_UNAVAILABLE;
    long version                                             OBJC2_UNAVAILABLE;
    long info                                                OBJC2_UNAVAILABLE;
    long instance_size                                       OBJC2_UNAVAILABLE;
    struct objc_ivar_list * _Nullable ivars                  OBJC2_UNAVAILABLE;
    struct objc_method_list * _Nullable * _Nullable methodLists                    OBJC2_UNAVAILABLE;
    struct objc_cache * _Nonnull cache                       OBJC2_UNAVAILABLE;
    struct objc_protocol_list * _Nullable protocols          OBJC2_UNAVAILABLE;
#endif

} OBJC2_UNAVAILABLE;

class_copyProtocolList

/** 
 * Describes the protocols adopted by a class.
 * 
 * @param cls The class you want to inspect.
 * @param outCount On return, contains the length of the returned array. 
 *  If outCount is NULL, the length is not returned.
 * 
 * @return An array of pointers of type Protocol* describing the protocols adopted 
 *  by the class. Any protocols adopted by superclasses or other protocols are not included. 
 *  The array contains *outCount pointers followed by a NULL terminator. You must free the array with free().
 * 
 *  If cls adopts no protocols, or cls is Nil, returns NULL and *outCount is 0.
 */
 // 得到一个类遵守协议的个数
OBJC_EXPORT Protocol * __unsafe_unretained _Nonnull * _Nullable 
class_copyProtocolList(Class _Nullable cls, unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int count;
Protocol **protocolList = class_copyProtocolList([UITableViewController class], &count);
for (unsigned int i = 0; i < count; i  ) {
    Protocol *pro = protocolList[I];
    NSLog(@"%s", protocol_getName(pro));
}

打印:

TestProject[19640:180921] _UIKeyboardAutoRespondingScrollViewController
TestProject[19640:180921] UITableViewFocusDelegateLegacy
TestProject[19640:180921] UIViewControllerPreviewingDelegate
TestProject[19640:180921] UIViewControllerPreviewingDelegate_Deprecated
TestProject[19640:180921] UITableViewDelegate
TestProject[19640:180921] UITableViewDataSource

protocol_getProperty

/** 
 * Returns the specified property of a given protocol.
 * 
 * @param proto A protocol.
 * @param name The name of a property.
 * @param isRequiredProperty c YES searches for a required property, c NO searches for an optional property.
 * @param isInstanceProperty c YES searches for an instance property, c NO searches for a class property.
 * 
 * @return The property specified by e name, e isRequiredProperty, and e isInstanceProperty for e proto,
 *  or c NULL if none of e proto's properties meets the specification.
 */
 // 根据协议,属性名字返回一个属性
OBJC_EXPORT objc_property_t _Nullable
protocol_getProperty(Protocol * _Nonnull proto,
                     const char * _Nonnull name,
                     BOOL isRequiredProperty, BOOL isInstanceProperty)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("CatDelegate");
objc_property_t pro = protocol_getProperty(protocolA, "testMark", YES, YES);
NSLog(@"%s", property_getName(pro));

打印:

TestProject[25760:731912] testMark

objc_getProtocol

/* Working with Protocols */

/** 
 * Returns a specified protocol.
 * 
 * @param name The name of a protocol.
 * 
 * @return The protocol named e name, or c NULL if no protocol named e name could be found.
 * 
 * @note This function acquires the runtime lock.
 */
 // 获取名称为 name 的协议
OBJC_EXPORT Protocol * _Nullable
objc_getProtocol(const char * _Nonnull name)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocol = objc_getProtocol("UITableViewDataSource");

打印:

(lldb) po protocol
<Protocol: 0x107dbf5e0>
object_getIndexedIvars
/** 
 * Returns a pointer to any extra bytes allocated with an instance given object.
 * 
 * @param obj An Objective-C object.
 * 
 * @return A pointer to any extra bytes allocated with e obj. If e obj was
 *   not allocated with any extra bytes, then dereferencing the returned pointer is undefined.
 * 
 * @note This function returns a pointer to any extra bytes allocated with the instance
 *  (as specified by c class_createInstance with extraBytes>0). This memory follows the
 *  object's ordinary ivars, but may not be adjacent to the last ivar.
 * @note The returned pointer is guaranteed to be pointer-size aligned, even if the area following
 *  the object's last ivar is less aligned than that. Alignment greater than pointer-size is never
 *  guaranteed, even if the area following the object's last ivar is more aligned than that.
 * @note In a garbage-collected environment, the memory is scanned conservatively.
 */
// 得到一个
OBJC_EXPORT void * _Nullable object_getIndexedIvars(id _Nullable obj)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;
sel_getUid
/** 
 * Registers a method name with the Objective-C runtime system.
 * 
 * @param str A pointer to a C string. Pass the name of the method you wish to register.
 * 
 * @return A pointer of type SEL specifying the selector for the named method.
 * 
 * @note The implementation of this method is identical to the implementation of c sel_registerName.
 * @note Prior to OS X version 10.0, this method tried to find the selector mapped to the given name
 *  and returned c NULL if the selector was not found. This was changed for safety, because it was
 *  observed that many of the callers of this function did not check the return value for c NULL.
 */
// 向 runtime系统根据字符串注册一个方法,返回SEL
OBJC_EXPORT SEL _Nonnull sel_getUid(const char * _Nonnull str)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

((void (*)(id, SEL))(void *)objc_msgSend)((id)self, sel_getUid("testFormat"));

打印:

TestProject[22472:6820361] testFormat

protocol_copyPropertyList

/** 
 * Returns an array of the required instance properties declared by a protocol.
 * 
 * @note Identical to 
 * code
 * protocol_copyPropertyList2(proto, outCount, YES, YES);
 * endcode
 */
 // 获取一个指定协议的所有的属性,不包括方法
OBJC_EXPORT objc_property_t _Nonnull * _Nullable
protocol_copyPropertyList(Protocol * _Nonnull proto,
                          unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("CatDelegate");
unsigned int outCount;
objc_property_t *propertyList = protocol_copyPropertyList(protocolA, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    objc_property_t property = propertyList[I];
    NSLog(@"name --- %s", property_getName(property));
}

打印:

TestProject[26269:782402] name --- testMark

class_getProperty

/** 
 * Returns a property with a given name of a given class.
 * 
 * @param cls The class you want to inspect.
 * @param name The name of the property you want to inspect.
 * 
 * @return A pointer of type c objc_property_t describing the property, or
 *  c NULL if the class does not declare a property with that name, 
 *  or c NULL if e cls is c Nil.
 */
 // 返回一个属性,通过参数类,和名字
OBJC_EXPORT objc_property_t _Nullable
class_getProperty(Class _Nullable cls, const char * _Nonnull name)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

objc_property_t property_t = class_getProperty([Person class], "age");
const char *name = property_getName(property_t);
NSLog(@"%s", name);

打印:

TestProject[20119:217782] age

protocol_addProtocol

/** 
 * Adds an incorporated protocol to another protocol. The protocol being
 * added to must still be under construction, while the additional protocol
 * must be already constructed.
 * 
 * @param proto The protocol you want to add to, it must be under construction.
 * @param addition The protocol you want to incorporate into e proto, it must be registered.
 */
 // 添加一个已注册的协议到未注册的协议当中
 proto:未注册的协议
 addition:被添加的已注册协议

OBJC_EXPORT void
protocol_addProtocol(Protocol * _Nonnull proto, Protocol * _Nonnull addition) 
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

// 声明一个协议返回协议的实例
Protocol *protocol = objc_allocateProtocol("ProjectDelegate");
objc_registerProtocol(protocol);   // 协议方法已经注册

Protocol *testProtocol = objc_allocateProtocol("TestProtocol");
protocol_addProtocol(testProtocol, protocol);

// 打印这个协议遵循的协议组
unsigned int count;
Protocol **protocolList = protocol_copyProtocolList(testProtocol, &count);
for (unsigned int i = 0; i < count; i  ) {
    Protocol *protocolC = protocolList[I];
    NSLog(@"name --- %s", protocol_getName(protocolC));
}

打印:

TestProject[32945:1206976] name --- ProjectDelegate
方法

objc_class

objc_allocateProtocol

/** 
 * Creates a new protocol instance that cannot be used until registered with
 * c objc_registerProtocol()
 * 
 * @param name The name of the protocol to create.
 *
 * @return The Protocol instance on success, c nil if a protocol
 *  with the same name already exists. 
 * @note There is no dispose method for this. 
 */
 // 创建一个新的协议实例,但是需要通过 objc_registerProtocol 注册使用
OBJC_EXPORT Protocol * _Nullable
objc_allocateProtocol(const char * _Nonnull name) 
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

Protocol *protocol = objc_allocateProtocol("PersonDelegate");

打印:

(lldb) po protocol
<__IncompleteProtocol: 0x6080000a84c0>

objc_allocateClassPair

/* Adding Classes */

/** 
 * Creates a new class and metaclass.
 * 
 * @param superclass The class to use as the new class's superclass, or c Nil to create a new root class.
 * @param name The string to use as the new class's name. The string will be copied.
 * @param extraBytes The number of bytes to allocate for indexed ivars at the end of 
 *  the class and metaclass objects. This should usually be c 0.
 * 
 * @return The new class, or Nil if the class could not be created (for example, the desired name is already in use).
 * 
 * @note You can get a pointer to the new metaclass by calling c object_getClass(newClass).
 * @note To create a new class, start by calling c objc_allocateClassPair. 
 *  Then set the class's attributes with functions like c class_addMethod and c class_addIvar.
 *  When you are done building the class, call c objc_registerClassPair. The new class is now ready for use.
 * @note Instance methods and instance variables should be added to the class itself. 
 *  Class methods should be added to the metaclass.
 */
功能:创建一个新的类和这个元类
去创建一个新的类开始通过objc_allocateClassPair,然后设置类的属性和功能用class_addMethod和class_addIvar,实例化方法和实例化变量应该被添加到类本身,类应该添加到元类中。
OBJC_EXPORT Class _Nullable
objc_allocateClassPair(Class _Nullable superclass, const char * _Nonnull name, 
                       size_t extraBytes) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

object_copy

/** 
 * Returns a copy of a given object.
 * 
 * @param obj An Objective-C object.
 * @param size The size of the object e obj.
 * 
 * @return A copy of e obj.
 */
// 对象的 copy 属于深 copy
OBJC_EXPORT id _Nullable object_copy(id _Nullable obj, size_t size)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

NSLog(@"self --- %p", self);
NSLog(@"object_copy --- %p", object_copy(self, sizeof(self)));

打印:

TestProject[23793:6934176] self --- 0x7f9f8c4049e0
TestProject[23793:6934176] object_copy --- 0x7f9f8c70a1d0
class_getName
/* Working with Classes */

/** 
 * Returns the name of a class.
 * 
 * @param cls A class object.
 * 
 * @return The name of the class, or the empty string if e cls is c Nil.
 */
 // 返回一个类的名字
OBJC_EXPORT const char * _Nonnull
class_getName(Class _Nullable cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"%s", class_getName([self class]));

打印:

TestProject[41376:7786142] ViewController

protocol_getName

/** 
 * Returns the name of a protocol.
 * 
 * @param p A protocol.
 * 
 * @return The name of the protocol e p as a C string.
 */
 根据协议得到协议的名称
OBJC_EXPORT const char * _Nonnull
protocol_getName(Protocol * _Nonnull proto)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("UITableViewDataSource");
NSLog(@"%s", protocol_getName(protocolA));

打印:

TestProject[23900:551699] UITableViewDataSource

objc_copyClassNamesForImage

代码:

unsigned int outCount;
const char **nameList = objc_copyClassNamesForImage("/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/UIKit.framework/UIKit", &outCount);
for (unsigned i = 0; i < outCount; i  ) {
    const char *name = nameList[I];
    NSLog(@"name: %s", name);
}

打印:

部分数据:
TestProject[34509:1304491] name: _UIPreviewPresentationPlatterView
TestProject[34509:1304491] name: UIKeyboardUISettings
TestProject[34509:1304491] name: _UIPickerViewTopFrame
TestProject[34509:1304491] name: _UIOnePartImageView
TestProject[34509:1304491] name: _UIPickerViewSelectionBar
TestProject[34509:1304491] name: _UIPickerWheelView
TestProject[34509:1304491] name: _UIPickerViewTestParameters
TestProject[34509:1304491] name: UIPickerView
ivar_getTypeEncoding
/** 
 * Returns the type string of an instance variable.
 * 
 * @param v The instance variable you want to enquire about.
 * 
 * @return A C string containing the instance variable's type encoding.
 *
 * @note For possible values, see Objective-C Runtime Programming Guide > Type Encodings.
 */
OBJC_EXPORT const char * _Nullable
ivar_getTypeEncoding(Ivar _Nonnull v) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = object_getInstanceVariable(p1, "_manTest", nil);
NSLog(@"%s", ivar_getTypeEncoding(ivar));

打印:

TestProject[23004:6857088] @"NSString"

objc_copyImageNames

/* Working with Libraries */

/** 
 * Returns the names of all the loaded Objective-C frameworks and dynamic
 * libraries.
 * 
 * @param outCount The number of names returned.
 * 
 * @return An array of C strings of names. Must be free()'d by caller.
 */
 // 返回所有已加载的 Objective-C 框架和动态库的名称
OBJC_EXPORT const char * _Nonnull * _Nonnull
objc_copyImageNames(unsigned int * _Nullable outCount) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int outCount;
const char **nameList = objc_copyImageNames(&outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    const char *name = nameList[I];
    NSLog(@"name : %s", name);
}
free(nameList);

打印:

TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/system/introspection/libdispatch.dylib
TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/system/libxpc.dylib
TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/system/libsystem_trace.dylib
TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/system/libsystem_network.dylib
TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/libobjc.A.dylib
TestProject[34100:1278609] name : /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 10.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/libate.dylib
sel_isMapped
/** 
 * Identifies a selector as being valid or invalid.
 * 
 * @param sel The selector you want to identify.
 * 
 * @return YES if selector is valid and has a function implementation, NO otherwise. 
 * 
 * @warning On some platforms, an invalid reference (to invalid memory addresses) can cause
 *  a crash. 
 */
// 判断 SEL 是否存在在 SEL Dictionary
OBJC_EXPORT BOOL sel_isMapped(SEL _Nonnull sel)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

SEL sel;
if (sel_isMapped(sel)) {
        NSLog(@"有效");
}

打印:

没有打印
class_getInstanceSize
/** 
 * Returns the size of instances of a class.
 * 
 * @param cls A class object.
 * 
 * @return The size in bytes of instances of the class e cls, or c 0 if e cls is c Nil.
 */
 // 返回实例类的大小,以字节为单位
OBJC_EXPORT size_t
class_getInstanceSize(Class _Nullable cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

NSLog(@"%ld", class_getInstanceSize([self class]));

打印:

TestProject[42305:7873713] 760

动态库

class_replaceMethod

/** 
 * Replaces the implementation of a method for a given class.
 * 
 * @param cls The class you want to modify.
 * @param name A selector that identifies the method whose implementation you want to replace.
 * @param imp The new implementation for the method identified by name for the class identified by cls.
 * @param types An array of characters that describe the types of the arguments to the method. 
 *  Since the function must take at least two arguments—self and _cmd, the second and third characters
 *  must be “@:” (the first character is the return type).
 * 
 * @return The previous implementation of the method identified by e name for the class identified by e cls.
 * 
 * @note This function behaves in two different ways:
 *  - If the method identified by e name does not yet exist, it is added as if c class_addMethod were called. 
 *    The type encoding specified by e types is used as given.
 *  - If the method identified by e name does exist, its c IMP is replaced as if c method_setImplementation were called.
 *    The type encoding specified by e types is ignored.
 */
// 替换给定类方法的实现,如果方法不存在则会调用class_addMethod添加方法。如果方法标识确实存在那么会调用method_setImplementation设置实现
OBJC_EXPORT IMP _Nullable
class_replaceMethod(Class _Nullable cls, SEL _Nonnull name, IMP _Nonnull imp, 
                    const char * _Nullable types) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);
object_setInstanceVariable
/** 
 * Changes the value of an instance variable of a class instance.
 * 
 * @param obj A pointer to an instance of a class. Pass the object containing
 *  the instance variable whose value you wish to modify.
 * @param name A C string. Pass the name of the instance variable whose value you wish to modify.
 * @param value The new value for the instance variable.
 * 
 * @return A pointer to the c Ivar data structure that defines the type and 
 *  name of the instance variable specified by e name.
 *
 * @note Instance variables with known memory management (such as ARC strong and weak)
 *  use that memory management. Instance variables with unknown memory management 
 *  are assigned as if they were unsafe_unretained.
 */
 //  给类动态的添加一个变量
OBJC_EXPORT Ivar _Nullable
object_setInstanceVariable(id _Nullable obj, const char * _Nonnull name,
                           void * _Nullable value)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

Person *p1 = [[Person alloc] init];
object_setInstanceVariableWithStrongDefault(p1, "_manTest", @"shuaibi");

objc_property_t

object_getIvar
/** 
 * Reads the value of an instance variable in an object.
 * 
 * @param obj The object containing the instance variable whose value you want to read.
 * @param ivar The Ivar describing the instance variable whose value you want to read.
 * 
 * @return The value of the instance variable specified by e ivar, or c nil if e object is c nil.
 * 
 * @note c object_getIvar is faster than c object_getInstanceVariable if the Ivar
 *  for the instance variable is already known.
 */
1. 读取对象中,实例变量的值
OBJC_EXPORT id _Nullable
object_getIvar(id _Nullable obj, Ivar _Nonnull ivar) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
    Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");
    id mantest = object_getIvar(p1, ivar);
    NSLog(@"%@", mantest);

打印:

TestProject[22563:6825947] chen test
objc_getRequiredClass
/** 
 * Returns the class definition of a specified class.
 * 
 * @param name The name of the class to look up.
 * 
 * @return The Class object for the named class.
 * 
 * @note This function is the same as c objc_getClass, but kills the process if the class is not found.
 * @note This function is used by ZeroLink, where failing to find a class would be a compile-time link error without ZeroLink.
 */
 // 获取指定类,如果这个类不存在则崩溃
OBJC_EXPORT Class _Nonnull
objc_getRequiredClass(const char * _Nonnull name)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Class cl1 = objc_getRequiredClass("Ca");

/** 
 * Returns the value of a property attribute given the attribute name.
 * 
 * @param property The property whose attribute value you are interested in.
 * @param attributeName C string representing the attribute name.
 *
 * @return The value string of the attribute e attributeName if it exists in
 *  e property, c nil otherwise. 
 */
 // 通过属性的名字得到属性的值
OBJC_EXPORT char * _Nullable
property_copyAttributeValue(objc_property_t _Nonnull property,
                            const char * _Nonnull attributeName)
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

id lenderClass = objc_getClass("Person");
unsigned int outCount;
objc_property_t *properties = class_copyPropertyList(lenderClass, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    objc_property_t property = properties[I];
    fprintf(stdout, "%s %sn", property_getName(property), property_getAttributes(property));

    unsigned int attrCount = 0;
    objc_property_attribute_t *attrs = property_copyAttributeList(property, &attrCount);
    for (unsigned int j = 0; j < attrCount; j  ) {
        objc_property_attribute_t attr = attrs[j];
        const char *name = attr.name;
        const char *value = attr.value;
        const char *test = property_copyAttributeValue(property, name);
        NSLog(@"属性的描述: %s 值: %s", name, value);
        NSLog(@"test -- %s", test);
    }
}

打印:

manTest T@"NSString",&,N,V_manTest
TestProject[23099:496137] 属性的描述: T 值: @"NSString"
TestProject[23099:496137] test -- @"NSString"
TestProject[23099:496137] 属性的描述: & 值: 
TestProject[23099:496137] test -- 
TestProject[23099:496137] 属性的描述: N 值: 
TestProject[23099:496137] test -- 
TestProject[23099:496137] 属性的描述: V 值: _manTest
TestProject[23099:496137] test -- _manTest

age Tq,N,V_age
TestProject[23099:496137] 属性的描述: T 值: q
TestProject[23099:496137] test -- q
TestProject[23099:496137] 属性的描述: N 值: 
TestProject[23099:496137] test -- 
TestProject[23099:496137] 属性的描述: V 值: _age
TestProject[23099:496137] test -- _age
定义
/// An opaque type that represents a method selector.
typedef struct objc_selector *SEL;

method_setImplementation

/** 
 * Sets the implementation of a method.
 * 
 * @param m The method for which to set an implementation.
 * @param imp The implemention to set to this method.
 * 
 * @return The previous implementation of the method.
 */
OBJC_EXPORT IMP _Nonnull
method_setImplementation(Method _Nonnull m, IMP _Nonnull imp) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Method m1 = class_getInstanceMethod([TestClass class], @selector(testLog1));
Method m2 = class_getInstanceMethod([TestClass class], @selector(testLog2));
IMP imp1 = method_getImplementation(m1);
IMP imp2 = method_getImplementation(m2);
method_setImplementation(m1, imp2);
method_setImplementation(m2, imp1);

object_dispose

/** 
 * Frees the memory occupied by a given object.
 * 
 * @param obj An Objective-C object.
 * 
 * @return nil
 */
 // 释放给定对象占用的内存
OBJC_EXPORT id _Nullable
object_dispose(id _Nullable obj)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

NSLog(@"%@",object_dispose(p1));

打印:

(lldb) po p1
<Person: 0x60000000ec50>

2018-03-09 17:15:38.690 YZTestProject[24032:6953790] (null)
(lldb) po p1
0x000060000000ec50

objc_property_t

定义:

/// An opaque type that represents an Objective-C declared property.
typedef struct objc_property *objc_property_t;
objc_getClassList
/** 
 * Obtains the list of registered class definitions.
 * 
 * @param buffer An array of c Class values. On output, each c Class value points to
 *  one class definition, up to either e bufferCount or the total number of registered classes,
 *  whichever is less. You can pass c NULL to obtain the total number of registered class
 *  definitions without actually retrieving any class definitions.
 * @param bufferCount An integer value. Pass the number of pointers for which you have allocated space
 *  in e buffer. On return, this function fills in only this number of elements. If this number is less
 *  than the number of registered classes, this function returns an arbitrary subset of the registered classes.
 * 
 * @return An integer value indicating the total number of registered classes.
 * 
 * @note The Objective-C runtime library automatically registers all the classes defined in your source code.
 *  You can create class definitions at runtime and register them with the c objc_addClass function.
 * 
 * @warning You cannot assume that class objects you get from this function are classes that inherit from c NSObject,
 *  so you cannot safely call any methods on such classes without detecting that the method is implemented first.
 */
 // 获取所有已经注册的类
OBJC_EXPORT int
objc_getClassList(Class _Nonnull * _Nullable buffer, int bufferCount)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);

代码:

Class *bufferClass;
int numClasses;
numClasses = objc_getClassList(NULL, 0);
if(numClasses > 0) {
    bufferClass = (Class *)malloc(sizeof(Class)*numClasses);
    numClasses = objc_getClassList(bufferClass, numClasses);
    NSLog(@"numer of classes: %d", numClasses);
    for (int i = 0; i < numClasses; i  ) {
        Class cls = bufferClass[i];
        NSLog(@"class name: %s", class_getName(cls));
    }
    free(bufferClass);
}

输出结果:

TestProject[41171:7767871] numer of classes: 4739

objc_setAssociatedObject

/** 
 * Sets an associated value for a given object using a given key and association policy.
 * 
 * @param object The source object for the association.
 * @param key The key for the association.
 * @param value The value to associate with the key key for object. Pass nil to clear an existing association.
 * @param policy The policy for the association. For possible values, see “Associative Object Behaviors.”
 * 
 * @see objc_setAssociatedObject
 * @see objc_removeAssociatedObjects
 */
 // 给已经存在的类添加私有属性,并且设置关联级别
OBJC_EXPORT void
objc_setAssociatedObject(id _Nonnull object, const void * _Nonnull key,
                         id _Nullable value, objc_AssociationPolicy policy)
    OBJC_AVAILABLE(10.6, 3.1, 9.0, 1.0, 2.0);

代码:

UIImage AddProperty.h
#import <UIKit/UIKit.h>
@interface UIImage (AddProperty)
@property(nonatomic,strong)NSString *imageWidth;
@end

UIImage AddProperty.m
#import "UIImage AddProperty.h"
#import <objc/runtime.h>

@implementation UIImage (AddProperty)

-(NSString *)imageWidth{
    return objc_getAssociatedObject(self, _cmd);
}

-(void)setImageWidth:(NSString *)imageWidth{
    objc_setAssociatedObject(self, @selector(imageWidth), imageWidth, OBJC_ASSOCIATION_ASSIGN);
}

@end

objc_registerClassPair

/** 
 * Registers a class that was allocated using c objc_allocateClassPair.
 * 
 * @param cls The class you want to register.
 */
// 注册创建的类
OBJC_EXPORT void
objc_registerClassPair(Class _Nonnull cls) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);
结构
struct objc_method {
    // 方法名字
    SEL _Nonnull method_name                                 OBJC2_UNAVAILABLE;
    // 方法类型
    char * _Nullable method_types                            OBJC2_UNAVAILABLE;
   // 方法指针
    IMP _Nonnull method_imp                                  OBJC2_UNAVAILABLE;
} 

object_getClass

/** 
 * Returns the class of an object.
 * 
 * @param obj The object you want to inspect.
 * 
 * @return The class object of which e object is an instance, 
 *  or c Nil if e object is c nil.
 */
 //  返回对象的类
OBJC_EXPORT Class _Nullable
object_getClass(id _Nullable obj) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Person *p1 = [[Person alloc] init];
NSLog(@"%@", object_getClass(p1));

打印:

TestProject[24120:6960612] Person
class_setSuperclass
/** 
 * Sets the superclass of a given class.
 * 
 * @param cls The class whose superclass you want to set.
 * @param newSuper The new superclass for cls.
 * 
 * @return The old superclass for cls.
 * 
 * @warning You should not use this function.
 */
 // 给类设置新的父类
OBJC_EXPORT Class _Nonnull
class_setSuperclass(Class _Nonnull cls, Class _Nonnull newSuper) 
    __OSX_DEPRECATED(10.5, 10.5, "not recommended") 
    __IOS_DEPRECATED(2.0, 2.0, "not recommended") 
    __TVOS_DEPRECATED(9.0, 9.0, "not recommended") 
    __WATCHOS_DEPRECATED(1.0, 1.0, "not recommended")
    __BRIDGEOS_DEPRECATED(2.0, 2.0, "not recommended");

代码:

NSLog(@"%@", class_getSuperclass(NSClassFromString(@"ViewController")));
    class_setSuperclass(NSClassFromString(@"ViewController"), NSClassFromString(@"UIImageView"));
    NSLog(@"%@", class_getSuperclass(NSClassFromString(@"ViewController")));

打印:

TestProject[41901:7839232] UIViewController
TestProject[41901:7839232] UIImageView

protocol_copyPropertyList2

/** 
 * Returns an array of properties declared by a protocol.
 * 
 * @param proto A protocol.
 * @param outCount Upon return, contains the number of elements in the returned array.
 * @param isRequiredProperty c YES returns required properties, c NO returns optional properties.
 * @param isInstanceProperty c YES returns instance properties, c NO returns class properties.
 * 
 * @return A C array of pointers of type c objc_property_t describing the properties declared by e proto.
 *  Any properties declared by other protocols adopted by this protocol are not included. The array contains
 *  c *outCount pointers followed by a c NULL terminator. You must free the array with c free().
 *  If the protocol declares no matching properties, c NULL is returned and c *outCount is c 0.
 */
 // 获取协议的所有的属性,分为required 和 optional。
 这个有点鸡肋我试了 optional 不起作用
OBJC_EXPORT objc_property_t _Nonnull * _Nullable
protocol_copyPropertyList2(Protocol * _Nonnull proto,
                           unsigned int * _Nullable outCount,
                           BOOL isRequiredProperty, BOOL isInstanceProperty)
    OBJC_AVAILABLE(10.12, 10.0, 10.0, 3.0, 2.0);

代码:

Protocol *protocolA = objc_getProtocol("CatDelegate");
unsigned int outCount;
if (@available(iOS 10.0, *)) {
    objc_property_t *propertyList = protocol_copyPropertyList2(protocolA, &outCount, NO, YES);
    for (unsigned int i = 0; i < outCount; i  ) {
        objc_property_t property = propertyList[I];
        NSLog(@"name --- %s", property_getName(property));
    }
} else {
    // Fallback on earlier versions
}

打印:

TestProject[26895:821115] name --- optionalMark
TestProject[26895:821115] name --- testMark

protocol_conformsToProtocol

/** 
 * Returns a Boolean value that indicates whether one protocol conforms to another protocol.
 * 
 * @param proto A protocol.
 * @param other A protocol.
 * 
 * @return c YES if e proto conforms to e other, otherwise c NO.
 * 
 * @note One protocol can incorporate other protocols using the same syntax 
 *  that classes use to adopt a protocol:
 *  code
 *  @protocol ProtocolName < protocol list >
 *  endcode
 *  All the protocols listed between angle brackets are considered part of the ProtocolName protocol.
 */
 // 判断一个协议是否遵从了另外一个协议,第一个协议是否遵守了第二个协议
OBJC_EXPORT BOOL
protocol_conformsToProtocol(Protocol * _Nullable proto,
                            Protocol * _Nullable other)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

Protocol *tableViewDelegate = objc_getProtocol("UITableViewDelegate");
Protocol *scrollViewDelegate = objc_getProtocol("UIScrollViewDelegate");
BOOL isConform = protocol_conformsToProtocol(tableViewDelegate, scrollViewDelegate);

打印:

(lldb) po isConform
YES
点进去,可以看到第一个协议确实遵守了第二个协议

class_respondsToSelector

/** 
 * Returns a Boolean value that indicates whether instances of a class respond to a particular selector.
 * 
 * @param cls The class you want to inspect.
 * @param sel A selector.
 * 
 * @return c YES if instances of the class respond to the selector, otherwise c NO.
 * 
 * @note You should usually use c NSObject's c respondsToSelector: or c instancesRespondToSelector: 
 *  methods instead of this function.
 */
 // 返回一个 Boolean 判断该类是否实现了指定的方法
OBJC_EXPORT BOOL
class_respondsToSelector(Class _Nullable cls, SEL _Nonnull sel) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

BOOL isYES = class_respondsToSelector([self class], @selector(viewWillAppear:));

打印:

(lldb) po isYES
YES
object_getInstanceVariable
/** 
 * Obtains the value of an instance variable of a class instance.
 * 
 * @param obj A pointer to an instance of a class. Pass the object containing
 *  the instance variable whose value you wish to obtain.
 * @param name A C string. Pass the name of the instance variable whose value you wish to obtain.
 * @param outValue On return, contains a pointer to the value of the instance variable.
 * 
 * @return A pointer to the c Ivar data structure that defines the type and name of
 *  the instance variable specified by e name.
 */
// 获取实例的实例变量的值
OBJC_EXPORT Ivar _Nullable
object_getInstanceVariable(id _Nullable obj, const char * _Nonnull name,
                           void * _Nullable * _Nullable outValue)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0)
    OBJC_ARC_UNAVAILABLE;

代码:

Person *p1 = [[Person alloc] init];
Ivar ivar = class_getInstanceVariable([p1 class], "_manTest");
class_copyIvarList
/** 
 * Describes the instance variables declared by a class.
 * 
 * @param cls The class to inspect.
 * @param outCount On return, contains the length of the returned array. 
 *  If outCount is NULL, the length is not returned.
 * 
 * @return An array of pointers of type Ivar describing the instance variables declared by the class. 
 *  Any instance variables declared by superclasses are not included. The array contains *outCount 
 *  pointers followed by a NULL terminator. You must free the array with free().
 * 
 *  If the class declares no instance variables, or cls is Nil, NULL is returned and *outCount is 0.
 */
 // 一个 Ivar 类型的指针数组,用于描述该类声明的实例变量,必须用free释放该数组
OBJC_EXPORT Ivar _Nonnull * _Nullable
class_copyIvarList(Class _Nullable cls, unsigned int * _Nullable outCount) 
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int count;
Ivar *ivars = class_copyIvarList([Person class], &count);
for (unsigned int i = 0; i < count; i  ) {
    Ivar ivar = ivars[I];
    const char *name = ivar_getName(ivar);
    const char *type = ivar_getTypeEncoding(ivar);
    NSLog(@"类型为%s 的 %s", type, name);

}
free(ivars);

打印:

TestProject[42937:7913951] 类型为@"NSString" 的 _manTest
object_getClassName
/** 
 * Returns the class name of a given object.
 * 
 * @param obj An Objective-C object.
 * 
 * @return The name of the class of which e obj is an instance.
 */
// 返回这个实例化类的名字
OBJC_EXPORT const char * _Nonnull object_getClassName(id _Nullable obj)
    OBJC_AVAILABLE(10.0, 2.0, 9.0, 1.0, 2.0);
方法

protocol_copyMethodDescriptionList

/** 
 * Returns an array of method descriptions of methods meeting a given specification for a given protocol.
 * 
 * @param p A protocol.
 * @param isRequiredMethod A Boolean value that indicates whether returned methods should
 *  be required methods (pass YES to specify required methods).
 * @param isInstanceMethod A Boolean value that indicates whether returned methods should
 *  be instance methods (pass YES to specify instance methods).
 * @param outCount Upon return, contains the number of method description structures in the returned array.
 * 
 * @return A C array of c objc_method_description structures containing the names and types of e p's methods 
 *  specified by e isRequiredMethod and e isInstanceMethod. The array contains c *outCount pointers followed
 *  by a c NULL terminator. You must free the list with c free().
 *  If the protocol declares no methods that meet the specification, c NULL is returned and c *outCount is 0.
 * 
 * @note Methods in other protocols adopted by this protocol are not included.
 */
 // 得到方法描述列表
OBJC_EXPORT struct objc_method_description * _Nullable
protocol_copyMethodDescriptionList(Protocol * _Nonnull proto,
                                   BOOL isRequiredMethod,
                                   BOOL isInstanceMethod,
                                   unsigned int * _Nullable outCount)
    OBJC_AVAILABLE(10.5, 2.0, 9.0, 1.0, 2.0);

代码:

unsigned int outCount;
struct objc_method_description *descList = protocol_copyMethodDescriptionList(protocolA, YES, YES, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    struct objc_method_description desc = descList[I];
    char *types = desc.types;
    NSLog(@"name: %@, type: %s", NSStringFromSelector(desc.name), types);
}

打印:

TestProject[25150:681145] name: tableView:numberOfRowsInSection:, type: q32@0:8@16q24
TestProject[25150:681145] name: tableView:cellForRowAtIndexPath:, type: @32@0:8@16@24

protocol_addMethodDescription

/** 
 * Adds a method to a protocol. The protocol must be under construction.
 * 
 * @param proto The protocol to add a method to.
 * @param name The name of the method to add.
 * @param types A C string that represents the method signature.
 * @param isRequiredMethod YES if the method is not an optional method.
 * @param isInstanceMethod YES if the method is an instance method. 
 */
 // 给没有创建的协议添加指定的方法,已经注册的协议无法添加
OBJC_EXPORT void
protocol_addMethodDescription(Protocol * _Nonnull proto, SEL _Nonnull name,
                              const char * _Nullable types,
                              BOOL isRequiredMethod, BOOL isInstanceMethod) 
    OBJC_AVAILABLE(10.7, 4.3, 9.0, 1.0, 2.0);

代码:

Protocol *protocolB = objc_allocateProtocol("PersonDelegate");
protocol_addMethodDescription(protocolB, @selector(runtimeTestAction3), "v@:", NO, YES);
unsigned int outCount;
struct objc_method_description *descList = protocol_copyMethodDescriptionList(protocolB, NO, YES, &outCount);
for (unsigned int i = 0; i < outCount; i  ) {
    struct objc_method_description desc = descList[I];
    char *types = desc.types;
    NSLog(@"name: %@, type: %s", NSStringFromSelector(desc.name), types);
}

打印:

TestProject[29062:1027253] name: runtimeTestAction3, type: v@:

前言

学习开发只有两件事是值得做下去的。第一是国外人的书,第二是官方的文档。

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