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?


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
     }
  }

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.");
    }
}

您需要检查正确的状态,因为每个状态都有不同的行为。你很可能需要UIGestureRecognizerStateBegan状态和UILongPressGestureRecognizer。

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

...

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
    if(UIGestureRecognizerStateBegan == gesture.state) {
        // Called on start of gesture, do work here
    }

    if(UIGestureRecognizerStateChanged == gesture.state) {
        // Do repeated work here (repeats continuously) while finger is down
    }

    if(UIGestureRecognizerStateEnded == gesture.state) {
        // Do end work here when finger is lifted
    }
}

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;
         }
}

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.");
        }
}

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.");
        }
}

斯威夫特3.0:

func handleLongPress(sender: UILongPressGestureRecognizer) {

    if sender.state == .ended {
        print("Long press Ended")
    } else if sender.state == .began {
        print("Long press detected")
    }