ios - 将 UIPanGestureRecognizer 和 UISwipeGestureRecognizer 添加到同一 View 会导致在设置 requireGestureToFail 后发生冲突

Question

我在同一个 View 中添加了一个滑动手势识别器和一个平移手势识别器。这些手势应该相互排斥。

为了做到这一点，我添加了对滑动手势的约束

[swipeGesture requireGestureToFail:panGesture];

(因为平移手势应该优先)

问题是平移手势总是被调用 - 即使是在非常快速的滑动过程中也是如此。

为了克服这个问题，我将自己设为平移手势的代表。在委托(delegate)方法中我设置了一些代码如下:

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    // check if it is the relevant view
    if (gestureRecognizer.view == self.myViewWithTwoGestures)
    {
        // check that it is the pan gesture
        if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]])
        {
            UIPanGestureRecognizer *pan = (UIPanGestureRecognizer *)gestureRecognizer;
            CGPoint velocity = [pan velocityInView:gestureRecognizer.view];
            // added an arbitrary velocity for failure
            if (ABS(velocity.y) > 100)
            {
                // fail if the swipe was fast enough - this should allow the swipe gesture to be invoked
                return NO;
            }
        }
    }
    return YES;
}

是否有建议的速度来确保良好的行为？还有其他方法可以强制平移手势失败吗？

Answer 1

根据 Apple 文档 here (在 为两个手势识别器声明特定顺序 下)让 UIPanGestureRecognizer 和 UISwipeGestureRecognizer 在同一个 View 上工作的方法是要求UISwipeGesureRecognizer 在调用 UIPanGestureRecognizer 之前失败(与您编写的相反)。这可能与滑动手势也是平移手势这一事实有关，但反之不一定正确(请参阅此 SO 问题)。

我写了这段代码，它成功地识别了平移和滑动手势:

UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panned:)];
UISwipeGestureRecognizer * swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swiped:)];
[pan requireGestureRecognizerToFail:swipe];
swipe.direction = (UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight);

-(void)panned:(UIPanGestureRecognizer *)gesture
{
    NSLog(@"Pan");
}

-(void)swiped:(UISwipeGestureRecognizer *)gesture
{
    NSLog(@"Swipe");
}

这并不像您希望的那样有效(因为您需要滑动手势失败，所以在平移手势开始之前会有一小段延迟)但它确实有效。但是，您发布的代码使您能够根据自己的喜好微调手势。