如何检测 UICollectionView 中单元格上的双击 [英] How to detect double-taps on cells in a UICollectionView

问题描述

我想响应在 UICollectionView 中双击单元格，并通过双击操作取消单元格选择.

I want to respond to double-taps on cells in a UICollectionView, and have a double-tap action cancel cell selection.

这是我尝试过的:

UITapGestureRecognizer *tapRecogniser = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapGesture:)];
tapRecogniser.numberOfTapsRequired = 2;

 for (UITapGestureRecognizer *recogniser in [self.collectionView gestureRecognizers]) {
    [recogniser requireGestureRecognizerToFail:tapRecogniser];
}

[self.collectionView addGestureRecognizer:tapRecogniser];

也就是说，如果我的双击手势识别器成功，我会尝试让默认手势识别器失败.

That is, I am trying to get the default gesture recognisers to fail if my double-tap gesture recogniser succeeds.

这似乎不起作用，因为我的集合视图委托的 collectionView:didSelectItemAtIndexPath: 在双击后仍然被调用

This doesn't appear to work, as my collection view delegate's collectionView:didSelectItemAtIndexPath: is still getting called after a double-tap

Apple 的文档 在这一点上具有误导性，声称默认手势识别器是 UITapGestureRecognizer 子类的一个实例，因此可以使用 [recogniser isKindOfClass:[UITapGestureRecognizer class]] 轻松识别出它.代码>.不幸的是，这是一个错误.

Apple's documentation is misleading on this point, claiming that the default gesture recogniser is an instance of a UITapGestureRecognizer subclass, so it can be easily picked out with [recogniser isKindOfClass:[UITapGestureRecognizer class]]. Unfortunately this is an error.

推荐答案

我不明白你为什么需要 requireToFail.我在 UICollectionView 中使用双击，它不会干扰我的单击(用于选择).

I don't see why you need the requireToFail. I use double-taps in a UICollectionView and it doesn't interfere with my single taps (used for selection).

我使用以下:

UITapGestureRecognizer *doubleTapFolderGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(processDoubleTap:)];
[doubleTapFolderGesture setNumberOfTapsRequired:2];
[doubleTapFolderGesture setNumberOfTouchesRequired:1];
[self.view addGestureRecognizer:doubleTapFolderGesture];

那么，这个:

- (void) processDoubleTap:(UITapGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateEnded)
    {
        CGPoint point = [sender locationInView:collectionView];
        NSIndexPath *indexPath = [collectionView indexPathForItemAtPoint:point];
        if (indexPath)
        {
            NSLog(@"Image was double tapped");
        }
        else 
        {
            DoSomeOtherStuffHereThatIsntRelated;
        }
    }
}

似乎工作正常——双击被识别，我可以随意处理它(在这种情况下，我正在扩展文件夹的内容).但是单击会导致选择被点击的卖出，我没有为此编写任何手势识别.

Seems to working fine -- the double tap is recognized and I can handle it as I wish (in this case I'm expanding the contents of a folder). But a single-tap will cause the tapped sell to be selected, which I haven't written any gesture recognition for.

重要

我正在重新审视这个问题，因为我发现我的原始答案在某些情况下可能是错误的，并且有一个明显的修复方法似乎有效.

需要添加以下行:

doubleTapFolderGesture.delaysTouchesBegan = YES;

消除了单击单元格选择的干扰.这提供了更强大的设置.

which eliminates interference with the single tap for cell selection. This provides a much more robust setup.

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