在某些情况下，孩子如何忽略 UIGesture 并让 superview 处理它？

Question

我正在实现类似于 iOS 的内存管理器的东西。这是一个UICollectionView 和UICollectionViewCell 孩子。如果您在单元格上水平滑动，父级将向左平移。但是，如果您垂直滑动，单元格会随着您的手指移动。

在我的 UICollectionViewCell 子类中，我有：

- (id)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {        
        UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(didPan:)];
        pan.maximumNumberOfTouches = 1;
        pan.minimumNumberOfTouches = 1;
        [self addGestureRecognizer:pan];
    }
    return self;
}

不幸的是，现在所有子单元格都将处理平移手势。父母永远无法处理它们。

- (void)didPan:(UIPanGestureRecognizer *)gesture
{
    CGPoint velocity = [gesture velocityInView:self.superview];
    if (ABS(velocity.y) > ABS(velocity.x)) {
        // Move the cell with the finger
    } else {
        // Let the parent UICollectionView pan horizontally
    }
}

我已经知道如何用手指移动单元格，但我不知道如何做另一种情况：让子单元格忽略平移手势并让其父单元处理它。

Answer 1

您需要让单元格的平移手势识别器与集合视图的平移手势识别器同时识别。

有几种方法可以做到这一点，但一种方法是让您的单元格成为平移手势识别器的delegate 并实现此方法：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    // Either just return YES to allow your cell's gesture recognizer
    // to work simultaneously with all other recognizers:
    return YES;

    // Or you can decide whether your cell's pan gesture recognizer should
    // recognize simultaneously with otherGestureRecognizer. For example,
    // you could get a reference to your collection view's panGestureRecognizer
    // and only return YES if otherGestureRecognizer is equal to that recognizer:
    return otherGestureRecognizer == <your collection view's gesture recognizer>;
}