ios - 解决两个平移手势识别器之间的冲突

我有以下层次结构:

• 查看
  • subview

每个 View 都分配了 UIPanGestureRecognizer。外部平移手势识别器只对垂直平移感兴趣，所以我为此实现了委托(delegate)方法:

- (BOOL)gestureRecognizerShouldBeginUIPanGestureRecognizer *)panGestureRecognizer {
    CGPoint velocity = [panGestureRecognizer velocityInView:panGestureRecognizer.view];
    return fabs(velocity.y) > fabs(velocity.x);
}

但是，Subview 的平移手势在识别中始终优先。有没有办法让外部平移手势识别器先识别，如果失败， subview 的平移手势可以接管？

我尝试了同时识别并且它可以工作，但是两个识别器都开始平移:

- (BOOL)gestureRecognizerUIGestureRecognizer *)gestureRecognizer 

    shouldRecognizeSimultaneouslyWithGestureRecognizerUIGestureRecognizer *)otherGestureRecognizer {
        return YES;
    }

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Best Answer-推荐答案

从 iOS 7 开始，UIGestureRecognizerDelegate 协议(protocol)已经声明了两个代理方法来满足你的需要，你可以使用 |gestureRecognizer:shouldRequireFailureOfGestureRecognizer:| 或者 |gestureRecognizerShouldBegin:shouldBeRequiredToFailByGestureRecognizer:|但相反。

以下片段是我的 UIPanGestureRecognizer 委托(delegate)实现:

- (BOOL)gestureRecognizerShouldBeginUIPanGestureRecognizer *)panGestureRecognizer {
    CGPoint velocity = [panGestureRecognizer velocityInView:panGestureRecognizer.view];
    return fabs(velocity.y) > fabs(velocity.x);
}

- (BOOL)gestureRecognizerUIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizerUIGestureRecognizer *)otherGestureRecognizer{
    if (otherGestureRecognizer == panGestureOfSubView) {
        return YES;
    }

    return NO;
}

关于ios - 解决两个平移手势识别器之间的冲突，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29233465/