如果 UIGestureRecognizer 触发，如何取消按钮点击？

Question

更新：问题似乎是对另一个 GestureRecognizer 的依赖失败。请参阅此问题下面的评论和测试项目！

在我的 iPhone 应用程序中，我有一个包含多个 UIButtons 作为子视图的视图。该视图还有一个 UITapGestureRecognizer，它正在监听两根手指的点击。

当在视图上发生两指点击时，我不希望按钮对点击做出反应，即使其中一根手指位于按钮内。我认为这就是“cancelsTouchesInView”的用途，但这不起作用。

我现在的问题是：当识别手势时，如何告诉我的按钮忽略点击？

编辑：这是我的手势识别器。

UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleTapped:)];
[doubleTap setNumberOfTouchesRequired:2];
[doubleTap setNumberOfTapsRequired:1];
[doubleTap setCancelsTouchesInView:YES];
[doubleTap setDelaysTouchesBegan:YES];
[doubleTap setDelaysTouchesEnded:YES];
[self.view addGestureRecognizer:doubleTap];
[doubleTap release];

Answer 1

据苹果开发人员称，这是一个错误。我向 Apple 提交了错误报告。
非常感谢您的提示，Deepak 和 gcamp！

错误报告：

摘要：
将两个 UITapGestureRecognizer 添加到视图时，其中一个要求另一个失败 (requiresGestureRecognizerToFail:)，第一个手势识别器的 cancelsTouchesInView 属性将被忽略。

重现步骤：
1.创建两个UITapGestureRecognizer（r1和r2）
2. 将 r1 配置为需要两次触摸和一次点击，并延迟触摸开始
3. 将 r2 配置为需要两次触摸和两次点击，并延迟 TouchBegan
4.配置r1要求r2失败[r1 requestsGestureRecognizerToFail:r2]
5. 将r1和r2添加到视图中
6. 在视图中放置一个UIButton
7. 用两根手指点击视图，其中一根手指应该点击按钮。

预期结果：
r1 应该被识别并且按钮点击应该被取消（对于 UITapGestureRecognizers，cancelsTouchesInView 默认为 YES）。

实际结果：
r1 被识别，但按钮 TouchUpInside 事件也被触发。

回归：
一旦您删除了对 r2 的依赖（第 4 步），cancelTouchesInView 就可以很好地用于 r1。

Answer 2

UIGestureRecognizer 上有一种方法可以回答您的问题

- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer

基本上，您要求两次点击识别器在接受单击识别器之前失败。

所以，

[singleTapRecognizer requireGestureRecognizerToFail:twoTapRecognizer];

Answer 3

使用delaysTouchesBegan 属性。将其设置为YES。

替代

禁用按钮上的用户交互，并像前面提到的那样附加单指点击识别器。在点击处理程序中，检查点击是否落在按钮的范围内。如果它在按钮的范围内，请执行 [theButton sendActionsForControlEvents:UIControlEventTouchUpInside];。即使用户交互被禁用，这也会根据需要触发触摸事件。

Answer 4

马克，我遇到了同样的错误。如果你发布你的雷达#，我会在 bugreporter 中欺骗它。

我写了以下解决方法。我对 UITapGestureRecognizer 进行子类化，然后使用该子类来跟踪触发手势操作的触摸。如果我们在视图中的 TouchesEnded 中获得相同的触摸，我们将重定向到 TouchesCancelled。需要“immediateTarget”，因为视图上的touchesEnded 调用发生在手势的touchesEnded 之后但在调用手势的操作之前。

RPTapGestureRecognizer.h:

#import <UIKit/UIKit.h>
#import <UIKit/UIGestureRecognizerSubclass.h>

@interface RPTapGestureRecognizer : UITapGestureRecognizer

@property (nonatomic, retain) NSSet *lastTouches;

- (void)setImmediateTarget:(id)inTarget action:(SEL)inAction;

@end

RPTapGestureRecognizer.m:

#import "RPTapGestureRecognizer.h"

@interface RPTapGestureRecognizer ()
@property (nonatomic) SEL immediateAction;
@property (nonatomic, assign) id immediateTarget;
@end

@implementation RPTapGestureRecognizer

@synthesize lastTouches;
@synthesize immediateAction, immediateTarget;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    self.lastTouches = nil;

    [super touchesBegan:touches withEvent:event];
}

- (void)setImmediateTarget:(id)inTarget action:(SEL)inAction
{
    self.immediateTarget = inTarget;
    self.immediateAction = inAction;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIGestureRecognizerState startingState, finalState;

    startingState = self.state;
    [super touchesEnded:touches withEvent:event];
    finalState = self.state;

    if (startingState != finalState &&
        finalState == UIGestureRecognizerStateEnded) {
        /* Must copy; the underlying NSCFSet will be modified by the superclass, removing the touches */
        self.lastTouches = [[touches copy] autorelease];

        if (self.immediateAction)
            [self.immediateTarget performSelector:self.immediateAction
                                       withObject:self];
    }
}

- (void)dealloc
{
    self.lastTouches = nil;
    self.immediateTarget = nil;

    [super dealloc];
}

@end

视图中：

@synthesize lastTapGesture

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    if (self.lastTapGesture && [self.lastTapGesture.lastTouches isEqualToSet:touches]) {
        [self touchesCancelled:touches withEvent:event];
        self.lastTapGesture = nil;
        return;
    }
 /* touches ended implementation here */
}

 - (void)willHandleMouseTapGesture:(RPTapGestureRecognizer *)tapGesture
{
    /* Because one tap gesture is dependent upon another, the touchesEnded method is still going to be called, instead of touchesCanceled.
     * This is an Apple bug against all versions of iOS at least up to 5.0. It will be called in the run loop before tapGesture's action is called.
     *
     * See http://stackoverflow.com/questions/6188997/how-to-cancel-button-tap-if-uigesturerecognizer-fires/6211922#6211922 for details.
     */
    self.lastTapGesture = tapGesture;
}

- (void)configureGestures
{
    /* Two finger taps */
     RPTapGestureRecognizer *tapGestureOne;
     tapGestureOne = [[[RPTapGestureRecognizer alloc] initWithTarget:self 
                                                              action:@selector(handleMouseTapGesture:)] autorelease];
     tapGestureOne.numberOfTapsRequired = 1;
     tapGestureOne.numberOfTouchesRequired = 2;
     [tapGestureOne setImmediateTarget:self action:@selector(willHandleMouseTapGesture:)];
     [self addGestureRecognizer:tapGestureOne];
     [myGestures addObject:tapGestureOne];

     RPTapGestureRecognizer *tapGestureTwo;
     tapGestureTwo = [[[RPTapGestureRecognizer alloc] initWithTarget:self 
                                                              action:@selector(handleMouseTapGesture:)] autorelease];
     tapGestureTwo.numberOfTapsRequired = 2;
     tapGestureTwo.numberOfTouchesRequired = 2;
     [tapGestureTwo setImmediateTarget:self action:@selector(willHandleMouseTapGesture:)];
     [self addGestureRecognizer:tapGestureTwo];
}