点击手势增加，造成crash注意事项UITapGestureRecognizer

  //在一个View里面添加点击clickview返回手势
    UIView * clickView = [[UIView alloc]initWithFrame:CGRectMake(0,
0, __MainScreen_Width,__MainScreen_Height-self.contentView.height)];
    
    UITapGestureRecognizer* tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self
action:@selector(clickViewCancelMethod)];
    [self addSubview:clickView];
    [clickView addGestureRecognizer:tapGesture];

1：造成crash原因self和clickview位置放反，crash报错为不认识这个方法，
self是一个父view，父类的方法
target是self
增加手势的对象是clickview