runtime----获取属性,方法,成员变量,协议

      unsigned int count;
      //获取属性列表
      objc_property_t *propertyList = class_copyPropertyList([Son class], &count); 
    for (unsigned int i=0; i%@", [NSString stringWithUTF8String:propertyName]);
    }  

 unsigned int count;
 //获取方法列表
    Method *methodList = class_copyMethodList([Son class], &count);
    for (unsigned int i = 0; i%@", NSStringFromSelector(method_getName(method)));
    }

  unsigned int count;
//获取成员变量列表
    Ivar *ivarList = class_copyIvarList([Son class], &count);
    for (unsigned int i = 0; i%@", [NSString stringWithUTF8String:ivarName]);
    }

  unsigned int count;
   //获取协议列表
    __unsafe_unretained Protocol **protocolList = class_copyProtocolList([Son class], &count);
    for (unsigned int i = 0 ; i%@", [NSString stringWithUTF8String:protocolName]);
    }

//方法交换
- (void)exchangeMethod {
    //获得viewController的生命周期方法的selector
    SEL systemSel = @selector(run);
    //自己实现的将要被交换的方法的selector
    SEL mySel = @selector(noRun);
    //两个方法的Method
    Method systemMethod = class_getInstanceMethod([self class], systemSel);
    Method myMethod = class_getInstanceMethod([self class], mySel);
    
    //首先动态添加方法，实现是被交换的方法，返回值表示添加成功还是失败
    BOOL isAdd = class_addMethod([Son class], systemSel, method_getImplementation(myMethod), method_getTypeEncoding(myMethod));
    if (isAdd) {
        //如果成功，说明类中不存在这个方法的实现
        //将被交换方法的实现替换到这个并不存在的实现
        class_replaceMethod([Son class], mySel, method_getImplementation(systemMethod), method_getTypeEncoding(systemMethod));
    }else{
        //否则，交换两个方法的实现
        method_exchangeImplementations(systemMethod, myMethod);
    }
}