id objc_msgSend(id self, SEL _cmd, ...) {

  Class class = object_getClass(self);

  IMP imp = class_getMethodImplementation(class, _cmd);

  return imp ? imp(self, _cmd, ...) : 0;

}

struct objc_class {

    Class isa  OBJC_ISA_AVAILABILITY;


#if !__OBJC2__

    Class super_class                                        OBJC2_UNAVAILABLE;

    const char *name                                         OBJC2_UNAVAILABLE;

    long version                                             OBJC2_UNAVAILABLE;

    long info                                                OBJC2_UNAVAILABLE;

    long instance_size                                       OBJC2_UNAVAILABLE;

    struct objc_ivar_list *ivars                             OBJC2_UNAVAILABLE;

    struct objc_method_list **methodLists                    OBJC2_UNAVAILABLE;

    struct objc_cache *cache                                 OBJC2_UNAVAILABLE;

    struct objc_protocol_list *protocols                     OBJC2_UNAVAILABLE;

#endif


} OBJC2_UNAVAILABLE;

struct objc_ivar_list {

    int ivar_count                                     OBJC2_UNAVAILABLE;

#ifdef __LP64__

    int space                                            OBJC2_UNAVAILABLE;

#endif

    /* variable length structure */

    struct objc_ivar ivar_list[1]                   OBJC2_UNAVAILABLE;

}                                                            OBJC2_UNAVAILABLE;

 

struct objc_method_list {

    struct objc_method_list *obsolete                  OBJC2_UNAVAILABLE;

 

    int method_count                                         OBJC2_UNAVAILABLE;

#ifdef __LP64__

    int space                                                      OBJC2_UNAVAILABLE;

#endif

    /* variable length structure */

    struct objc_method method_list[1]                  OBJC2_UNAVAILABLE;

}

struct objc_ivar {

    char *ivar_name                                          OBJC2_UNAVAILABLE;

    char *ivar_type                                          OBJC2_UNAVAILABLE;

    int ivar_offset                                          OBJC2_UNAVAILABLE;

#ifdef __LP64__

    int space                                                OBJC2_UNAVAILABLE;

#endif

}  

#import <objc/runtime.h>

-(NSString *)nameWithInstance:(id)instance {

    unsigned int numIvars = 0;

    NSString *key=nil;

    Ivar * ivars = class_copyIvarList([self class], &numIvars);

    for(int i = 0; i < numIvars; i++) {

        Ivar thisIvar = ivars[i];

        const char *type = ivar_getTypeEncoding(thisIvar);

        NSString *stringType =  [NSString stringWithCString:type encoding:NSUTF8StringEncoding];

        if (![stringType hasPrefix:@"@"]) {

            continue;

        }

        if ((object_getIvar(self, thisIvar) == instance)) {//此处若 crash 不要慌！

            key = [NSString stringWithUTF8String:ivar_getName(thisIvar)];

            break;

        }

    }

    free(ivars);

    return key;

}

     //遍历UIPageControl属性
      unsigned int count = 0;
      Ivar *ivars = class_copyIvarList([UIPageControl class], &count);
      for (int i = 0; i < count; i++) {
          Ivar ivar = ivars[i];
          //获取所有私有属性
          const char *property = ivar_getName(ivar);
          NSLog(@"%@",[[NSString alloc]initWithCString:property encoding:NSUTF8StringEncoding]);
      }

struct objc_cache {

    unsigned int mask /* total = mask + 1 */                 OBJC2_UNAVAILABLE;

    unsigned int occupied                                    OBJC2_UNAVAILABLE;

    Method buckets[1]                                        OBJC2_UNAVAILABLE;

};

@interface Lender : NSObject {

    float alone;

}

@property float alone;

@end

#import <objc/runtime.h>

#import "Lenaer.h"

 

 id LenderClass = objc_getClass("Lender");

unsigned int outCount, i;

objc_property_t *properties = class_copyPropertyList(LenderClass, &outCount);

for (i = 0; i < outCount; i++) {

    objc_property_t property = properties[i];

    fprintf(stdout, "%s %s\n", property_getName(property), property_getAttributes(property));

} 

//
//  RuntimeMain.h
//  RuntimeTest
//
//  Created by Vie on 2017/2/8.
//  Copyright © 2017年 Vie. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface RuntimeMain : NSObject

@end

//
//  RuntimeMain.m
//  RuntimeTest
//
//  Created by Vie on 2017/2/8.
//  Copyright © 2017年 Vie. All rights reserved.
//

#import "RuntimeMain.h"
#import <objc/runtime.h>
#import "RuntimeFoward.h"
@implementation RuntimeMain
#pragma mark 实例方法动态解析重定向
//动态实例方法解析，如果这里没有找到该执行的方法会指定到重定向forwardingTargetForSelector:方法
+(BOOL)resolveInstanceMethod:(SEL)sel{
        if (sel == @selector(goToSchool:)) {
            //用class_addMethod函数完成向特定类添加特定方法实现的操作
            //其中 “[email protected]:” 表示返回值和参数(为了兼容32位机型使用"[email protected]:@")，增加f处理float参数，这个符号涉及 Type Encoding
    
         return   class_addMethod([self class], sel, class_getMethodImplementation([self class], @selector(myInstanceMethod:)), "[email protected]:@");
    
        }
    
        return [super resolveInstanceMethod:sel];
}
//重定向实例方法，Lenaer实现了该实例方法；如果forwardingTargetForSelector：未找方法就转发给forwardInvocation:方法
//forwardingTargetForSelector:仅支持一个对象的返回，也就是说消息只能被转发给一个对象
-(id)forwardingTargetForSelector:(SEL)aSelector{

    if(aSelector == @selector(learnClass:)) {
        return [[NSClassFromString(@"RuntimeFoward") alloc] init];
    }
    //千万别返回self，因为那样会死循环。重定向的类未实现该方法会导致崩溃
    return [super forwardingTargetForSelector:aSelector];
}
//在forwardInvocation:之前创建一个有效的方法签名
-(NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector{
    //其中 “[email protected]:” 表示返回值和参数(为了兼容32位机型使用"[email protected]:@")，增加f处理float参数，这个符号涉及 Type Encoding
    return [NSMethodSignature signatureWithObjCTypes:"[email protected]:@"];
}
    //如果resolveInstanceMethod:和forwardingTargetForSelector:以及forwardInvocation:都未找到方法实现将崩溃，所以可以再最后else定义一个错误日志输出方法处理崩溃
    //forwardInvocation:可以将消息同时转发给任意多个对象
    //forwardInvocation:方法就像一个不能识别的消息的分发中心，将这些消息转发给不同接收对象。或者它也可以象一个运输站将所有的消息都发送给同一个接收对象。它可以将一个消息翻译成另外一个消息，或者简单的”吃掉“某些消息，因此没有响应也没有错误。forwardInvocation:方法也可以对不同的消息提供同样的响应，这一切都取决于方法的具体实现。该方法所提供是将不同的对象链接到消息链的能力。
-(void)forwardInvocation:(NSInvocation *)anInvocation{
    return [anInvocation invokeWithTarget:[[RuntimeFoward alloc] init]];
}
    
-(void)myInstanceMethod:(NSString *)string{
    
    NSLog(@"myInstanceMethod = %@", string);
    
}
    
#pragma mark 类方法动态解析重定向
    
    //动态类方法解析，如果这里没有找到该执行的方法会指定到重定向forwardingTargetForSelector:方法
+(BOOL)resolveClassMethod:(SEL)sel{
    
    if (sel==@selector(classFouction:)) {
        
        //用class_addMethod函数完成向特定类添加特定方法实现的操作
        
        //其中 “[email protected]:” 表示返回值和参数(为了兼容32位机型使用"[email protected]:@")增加f处理float参数，这个符号涉及 Type Encoding
        
        return  class_addMethod(object_getClass(self), sel, class_getMethodImplementation(object_getClass(self), @selector(myClassMethod:)), "[email protected]:@f");
        
    }
    
    return [class_getSuperclass(self) resolveClassMethod:sel];
    
}
    //重定向类方法，Lenaer实现了该类方法;如果resolveClassMethod:和forwardingTargetForSelector:都未找到方法实现将崩溃，所以可以再最后else定义一个错误日志输出方法处理崩溃
+(id)forwardingTargetForSelector:(SEL)aSelector{
    if(aSelector == @selector(testNotMe:)) {
        return NSClassFromString(@"RuntimeFoward") ;
    }
    //千万别返回self，因为那样会死循环。重定向的类未实现该方法会导致崩溃
    return [super forwardingTargetForSelector:aSelector];
}
+(void)myClassMethod:(NSString *)string{
    
    NSLog(@"myClassMethod = %@", string);
    
}
@end

//
//  RuntimeFoward.h
//  RuntimeTest
//
//  Created by Vie on 2017/2/8.
//  Copyright © 2017年 Vie. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface RuntimeFoward : NSObject
@end

//
//  RuntimeFoward.m
//  RuntimeTest
//
//  Created by Vie on 2017/2/8.
//  Copyright © 2017年 Vie. All rights reserved.
//

#import "RuntimeFoward.h"

@implementation RuntimeFoward
-(void)fowardGet{
    NSLog(@"消息转发给RuntimeFoward");
}

-(void)fowardWithString:(NSString *)string{
    NSLog(@"消息转发给RuntimeFoward,并带参数%@",string);
}
-(void)learnClass:(NSString *)string{
     NSLog(@"消息转发给RuntimeFoward,learnClass并带参数%@",string);
}
    
-(NSString *)getInfo:(NSString *)name height:(float)aHeight{
    return [NSString stringWithFormat:@"%@身高%f",name,aHeight];
}
-(float)getRectangularArea:(float)aWidth height:(float)aHeight{
    return aWidth*aHeight;
}
    
+(void)testNotMe:(NSString *)string{
   NSLog(@"消息转发给RuntimeFoward,testNotMe并带参数%@",string);
}

@end

#import <objc/message.h>
#import "RuntimeMain.h"

//调用实例方法
    RuntimeMain *runMain=[[RuntimeMain alloc] init];
    //调用无参数无返回值方法
    ((void (*) (id, SEL)) objc_msgSend) (runMain, sel_registerName("fowardGet"));
    //调用有参数无返回值方法
    ((void (*) (id, SEL,NSString *)) objc_msgSend)(runMain,sel_registerName("fowardWithString:"),@"哈哈哈");
    ((void (*) (id, SEL,NSString *)) objc_msgSend)(runMain,sel_registerName("goToSchool:"),@"哈哈哈");
    ((void (*) (id, SEL,NSString *)) objc_msgSend)(runMain,sel_registerName("learnClass:"),@"哈哈哈");
    //调用返回String有参数方法
   NSString *infoString= ((NSString* (*)(id,SEL,NSString *,float)) objc_msgSend)(runMain,sel_registerName("getInfo:height:"),@"张三",175.81);
    NSLog(@"%@",infoString);
    //调用返回float方法， 
    float area=((float (*) (id,SEL,float,float)) objc_msgSend)(runMain,sel_registerName("getRectangularArea:height:"),12.0f,12.0f);

    NSLog(@"获得长方形面积为%f",area);
    
    //调用类方法
    [RuntimeMain performSelector:@selector(classFouction:) withObject:@"xxx"];
    [RuntimeMain performSelector:@selector(testNotMe:) withObject:@"xxx"];

2017-02-08 19:33:30.608 RuntimeTest[26467:721253] 消息转发给RuntimeFoward
2017-02-08 19:33:30.609 RuntimeTest[26467:721253] 消息转发给RuntimeFoward,并带参数哈哈哈
2017-02-08 19:33:30.609 RuntimeTest[26467:721253] myInstanceMethod = 哈哈哈
2017-02-08 19:33:30.610 RuntimeTest[26467:721253] 消息转发给RuntimeFoward,learnClass并带参数哈哈哈
2017-02-08 19:33:30.611 RuntimeTest[26467:721253] 张三身高175.809998
2017-02-08 19:33:30.612 RuntimeTest[26467:721253] 获得长方形面积为144.000000
2017-02-08 19:33:30.613 RuntimeTest[26467:721253] myClassMethod = xxx
2017-02-08 19:33:30.616 RuntimeTest[26467:721253] 消息转发给RuntimeFoward,testNotMe并带参数xxx