如何检测同时手势的结束？ (iOS)

Posted 2023-03-13

【中文标题】如何检测同时手势的结束？ (iOS)

【英文标题】：How to detect the end of simultaneous gestures? (iOS)

【发布时间】：2011-10-18 12:00:23

【问题描述】：

在我的应用中，我同时使用 UIPinchGestureRecognizer、UIRotationGestureRecognizer 和 UIPanGestureRecognizer 来缩放、旋转和移动图像。

方法 gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: 总是返回 YES 并且图像处理效果很好，但是......如何检测所有同时手势的结束，以便我可以重置图像？

【参考方案1】：

一个简单的解决方案怎么样，比如计算当前正在处理的手势，并在所有手势结束时采取行动？

.h 文件：

int handledGesturesCount;

.m 文件：

- (id)init 
    (...)
    handledGesturesCount = 0;


// gesture handlers - the code for -pinch: repeats for -pan: and -rotate:
- (void)pinch:(UIPinchGestureRecognizer *)recognizer 
    if (recognizer.state == UIGestureRecognizerStateBegan) 
        handledGesturesCount += 1;
     else if (recognizer.state == UIGestureRecognizerStateEnded ||
               recognizer.state == UIGestureRecognizerStateCancelled ||
               recognizer.state == UIGestureRecognizerStateFailed)
    
        handledGesturesCount -= 1;
        if (handledGesturesCount == 0) 
            [self resetImage];
        
    


- (void)pan:(UIPanGestureRecognizer *)recognizer 
    if (recognizer.state == UIGestureRecognizerStateBegan) 
        handledGesturesCount += 1;
     else if (recognizer.state == UIGestureRecognizerStateEnded ||
               recognizer.state == UIGestureRecognizerStateCancelled ||
               recognizer.state == UIGestureRecognizerStateFailed)
    
        handledGesturesCount -= 1;
        if (handledGesturesCount == 0) 
            [self resetImage];
        
    


- (void)rotate:(UIRotationGestureRecognizer *)recognizer 
    if (recognizer.state == UIGestureRecognizerStateBegan) 
        handledGesturesCount += 1;
     else if (recognizer.state == UIGestureRecognizerStateEnded ||
               recognizer.state == UIGestureRecognizerStateCancelled ||
               recognizer.state == UIGestureRecognizerStateFailed)
    
        handledGesturesCount -= 1;
        if (handledGesturesCount == 0) 
            [self resetImage];
        
    

【讨论】：

当您涉及点击识别器时，此方法将失败。他们似乎在UIGestureRecognizerStateBegan 中发送消息，导致handledGesturesCount 减少到0 以下。