关联对象

-(UIImageView *)btnImageView

{

  // return objc_getAssociatedObject(self, @selector(isClicked));

    return objc_getAssociatedObject(self, &kbtnImageView);

}

//set

static char kbtnImageView;

-(void)setBtnImageView:(UIImageView *)btnImageView

{

    //如果是指针类型

    return objc_setAssociatedObject(self, &kbtnImageView, btnImageView, OBJC_ASSOCIATION_RETAIN);

    

    //1 源对象self

    //2 关键字 唯一静态变量key isClicked

    //3 关联的对象

    //4 关键策略  OBJC_ASSOCIATION_RETAIN_NONATOMIC

    //objc_setAssociatedObject(self, @selector(isClicked), @(isClicked), OBJC_ASSOCIATION_RETAIN_NONATOMIC);

   

}