PanGesture 和 Tap Gesture 之间的冲突

Question

我的应用由一副纸牌组成。卡片组中的大多数卡片都是在 draggableView 中制作的。我正在努力做到这一点，以便在屏幕上双击将使我在卡上的按钮消失/重新出现。阅读此post 后，我尝试尝试一下。我将 UITapGesture 放入了我的 draggableView 类的 initWithFrame 方法中，如下所示：

- (id)initWithFrame:(CGRect)frame
self = [super initWithFrame:frame];
if (self) {
    [self addSubviewFromNib];
    [self setupView];
    panGestureRecognizer = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(beingDragged:)];
    cardWidth = frame.size.width;
    cardHeight = frame.size.height;
    type = 0;
    panGestureRecognizer.delegate = self;
    panGestureRecognizer.cancelsTouchesInView = NO;
    _backgroundScrollView.panGestureRecognizer.cancelsTouchesInView = NO;
    //...more code above....
    _backgroundScrollView.userInteractionEnabled = YES;
    tapGestureRecognizer = [[UITapGestureRecognizer alloc]   initWithTarget:_backgroundScrollView action:@selector(doubleTap)];
    tapGestureRecognizer.delegate = _backgroundScrollView;
    tapGestureRecognizer.numberOfTapsRequired = 2;
[_backgroundScrollView addGestureRecognizer:tapGestureRecognizer];
[self addGestureRecognizer:panGestureRecognizer];

}

 - (void) doubleTap: (UITapGestureRecognizer *)tapGesturerecognizer{

    _mapButton.hidden = !_mapButton.hidden;
    _menuButton.hidden = !_menuButton.hidden;
    _phoneButton.hidden = !_phoneButton.hidden;
    reviewButton.hidden = !reviewButton.hidden;
    _shareButton.hidden = !_shareButton.hidden;

}


- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

    // If the gesture recognizer is a UITapGestureRecongizer, but the other
    // gesture detected is a UIPanGestureRecognizer, require the
    // UITapGestureRecognizer to fail.
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]] &&
        [otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        return YES;
    } else {
        return NO;
    }
}



- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
        return YES;
    }
    if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        UIPanGestureRecognizer *panGesture = (UIPanGestureRecognizer *)gestureRecognizer;
        CGPoint velocity = [panGesture velocityInView:self];
        return fabs(velocity.y) <= fabs(velocity.x);
    }
    return YES;
}

但是，如果我双击，我会收到这个 sib abrt 错误：

 -[UITapGestureRecognizer velocityInView:]: unrecognized selector sent to instance 0x7f9f9a244230
 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UITapGestureRecognizer velocityInView:]: unrecognized selector sent to instance 0x7f9f9a244230'

我假设这意味着 PanGestureRecognizer 和 TapGesture 识别器之间存在错误。我该如何解决？

编辑：仍未解决，但如果我将 tapGesture 添加到可拖动视图（因此，self）而不是 _backgroundScrollView，我会收到此错误：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[DraggableView doubleTap]: unrecognized selector sent to instance 0x7fefdd9e4f70'

其他编辑：我将它改回 backgroundScrollView，现在我得到这个错误：

[UIScrollView doubleTap]: unrecognized selector sent to instance 0x7fe5130af000

Answer 1

gestureRecognizerShouldBegin 将被调用，当手势识别器即将处理触摸时，它可能是点击手势，也可能是平移手势。您需要检查gestureRecogniser 类型，然后继续。

实现以下方法（取自here）以允许同时识别手势：

 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

    // If the gesture recognizer is a UITapGestureRecongizer, but the other
    // gesture detected is a UIPanGestureRecognizer, require the
    // UIPanGestureRecognizer to fail.
    if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]] &&
        [otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]])  {
       return YES;
    } else {
       return NO;
    }
}

在另一个委托方法中，崩溃原因告诉你：

-[UITapGestureRecognizer velocityInView:]: unrecognized selector sent to instance 0x7f9f9a2

velocityInView 被错误的手势类型调用，为避免此类错误，修改您的委托方法如下：

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer 
{
  if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {     
       return YES;
  }
  if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) { 
       UIPanGestureRecogniser *panGesture = (UIPanGestureRecongiser *)gestureRecogniser;    
       CGPoint velocity = [panGesture velocityInView:self];
       return fabs(velocity.y) <= fabs(velocity.x);
  }
   return YES;
}

Answer 2

我的错误： 在我的 h 文件中，我需要使用 draggableView 作为 tapGesture 的委托，然后将 gestureRecognizer 插入 UIGestureRecognizerDelegate 协议，如下所示：

@protocol UIGestureRecognizerDelegate <NSObject>
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;
@end