UILongPressGestureRecognizer在按下时被调用两次

我正在检测用户是否按下了2秒:

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
                                             initWithTarget:self 
                                             action:@selector(handleLongPress:)];
        longPress.minimumPressDuration = 2.0;
        [self addGestureRecognizer:longPress];
        [longPress release];

这是我处理长按的方法:

-(void)handleLongPress:(UILongPressGestureRecognizer*)recognizer{
    NSLog(@"double oo");
}

当我按下超过2秒时，文本“double oo”会打印两次。为什么会这样?我该如何解决?

当前回答

UILongPressGestureRecognizer是一个连续事件识别器。你必须观察状态，看看这是事件的开始、中间还是结束，并据此采取行动。也就是说，你可以在开始后抛弃所有事件，或者只看你需要的运动。来自职业参考:

长按手势是连续的。手势开始(UIGestureRecognizerStateBegan)时，允许的手指数量(numberOfTouchesRequired)已按下指定的时间(minimumPressDuration)和触摸不超出允许的移动范围(allowableMovement)。每当手指移动时，手势识别器就转换到Change状态，当任何手指抬起时，它就结束(UIGestureRecognizerStateEnded)。

现在你可以像这样跟踪状态

-  (void)handleLongPress:(UILongPressGestureRecognizer*)sender { 
    if (sender.state == UIGestureRecognizerStateEnded) {
      NSLog(@"UIGestureRecognizerStateEnded");
    //Do Whatever You want on End of Gesture
     }
    else if (sender.state == UIGestureRecognizerStateBegan){
       NSLog(@"UIGestureRecognizerStateBegan.");
   //Do Whatever You want on Began of Gesture
     }
  }

2010-07-23 16:41:05

其他回答

现在你可以像这样跟踪状态

-  (void)handleLongPress:(UILongPressGestureRecognizer*)sender { 
    if (sender.state == UIGestureRecognizerStateEnded) {
      NSLog(@"UIGestureRecognizerStateEnded");
    //Do Whatever You want on End of Gesture
     }
    else if (sender.state == UIGestureRecognizerStateBegan){
       NSLog(@"UIGestureRecognizerStateBegan.");
   //Do Whatever You want on Began of Gesture
     }
  }

2010-07-23 16:41:05

要检查UILongPressGestureRecognizer的状态，只需在selector方法上添加if语句:

- (void)handleLongPress:(UILongPressGestureRecognizer *)sender {    
    if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"Long press Ended");
    } else if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Long press detected.");
    }
}

2010-11-11 15:43:17

试试这个:

objective - c

- (void)handleLongPress:(UILongPressGestureRecognizer*)sender { 
    if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"Long press Ended");
    } else if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Long press detected.");
    }
}

斯威夫特2.2:

func handleLongPress(sender:UILongPressGestureRecognizer) {

        if (sender.state == UIGestureRecognizerState.Ended) {
            print("Long press Ended");
        } else if (sender.state == UIGestureRecognizerState.Began) {
            print("Long press detected.");
        }
}

2015-09-07 08:38:51

下面是如何在Swift中处理它:

func longPress(sender:UILongPressGestureRecognizer!) {

        if (sender.state == UIGestureRecognizerState.Ended) {
            println("Long press Ended");
        } else if (sender.state == UIGestureRecognizerState.Began) {
            println("Long press detected.");
        }
}

2014-09-24 21:29:13

您的手势处理程序接收每个手势状态的调用。因此，您需要对每个状态进行检查，并将代码置于必需状态。

一个人肯定更喜欢使用switch-case而不是if-else:

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
                                         initWithTarget:self 
                                         action:@selector(handleLongPress:)];
    longPress.minimumPressDuration = 1.0;
    [myView addGestureRecognizer:longPress];
    [longPress release];

-(void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
        switch(gesture.state){
          case UIGestureRecognizerStateBegan:
               NSLog(@"State Began");
               break;
          case UIGestureRecognizerStateChanged:
               NSLog(@"State changed");
               break;
          case UIGestureRecognizerStateEnded:
               NSLog(@"State End");
               break;
          default:
               break;
         }
}

2014-04-04 09:21:17

UILongPressGestureRecognizer在按下时被调用两次

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