同时使用触摸按下和触摸抬起手势识别器

Question

我在我的UIView上使用了两个手势识别器。一个是标准的UITapGestureRecognizer，另一个是我编写的非常简单的触摸按下识别器：

@implementation TouchDownGestureRecognizer

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    if (self.state == UIGestureRecognizerStatePossible) {
        self.state = UIGestureRecognizerStateRecognized;
    }
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    self.state = UIGestureRecognizerStateFailed;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    self.state = UIGestureRecognizerStateFailed;
}

@end

只有在我为它们分配一个包含此方法的委托时，它们才能一起工作：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    return YES;
}

一切正常运作，但是当我在该视图上进行长按时，按下触摸识别器会触发，而抬起触摸识别器则不会。对于短时间的点击，两个都可以被触发。

我实现了UIGestureRecognizerDelegate中的所有方法都返回了YES，但仍然无济于事。如果我添加日志以查看与委托的交互及自己的识别器内部情况，我可以看到对于短时间和长时间的点击，调用顺序是相同的——除了抬起触摸识别器的调用。我做错了哪些事情吗？

- Sergey Mikhanov

Answer 1

为什么不直接从UILongPressGestureRecognizer中检查touchUp？

-(void)selectionDetected:(UILongPressGestureRecognizer*)longPress
{
    if(longPress.state==1)
    {
       //long Press is being held down
    }
    else if(longPress.state==3)
    {
        //the touch has been picked up
    }
}

- Tommy Devoy

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非常好的建议，谢谢！那个识别器需要将 minimumPressDuration 设置为 0，现在可以正常工作了。 - Sergey Mikhanov