iOS UITapGestureRecognizer区分单击和双击

//添加单击手势监听
    UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapGesture:)];
    [singleTap setNumberOfTapsRequired:1];
    [self addGestureRecognizer:singleTap];
    
    
    self.maximumZoomScale = 4.0;
    
    //添加双击手势监听
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(doubleTap:)];
    [doubleTap setNumberOfTapsRequired:2];
    [self addGestureRecognizer:doubleTap];
    
    [singleTap requireGestureRecognizerToFail:doubleTap];  //加入这一行就不会出现这个问题