UICollectionView - 如果选择了单元格，则不调用 didDeselectItemAtIndexPath [英] UICollectionView - didDeselectItemAtIndexPath not called if cell is selected

问题描述

我要做的第一件事是设置选中的单元格.

The first thing I do is to set the cell selected.

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
    cell.selected = YES;
    return cell;
}

并且单元格被成功选中.如果用户触摸选定的单元格，则应取消选择该单元格并调用代表.但这永远不会发生.

And the cell is successfully selected. If the user touches the selected cell, than should the cell be deselected and the delegates be called. But this never happen.

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}

- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}

我知道如果我以编程方式设置选择，则不会调用代表.委托和数据源已设置.

I know that the delegates are not called if I set the selection programmatically. The delegate and datasource are set.

但是，这个委托被调用:

However, this delegate gets called:

- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath {
    NSLog(@"%s", __PRETTY_FUNCTION__);
    return YES;
}

如果我删除 cell.selected = YES 则一切正常.有没有人可以解释这种行为?

If I remove the cell.selected = YES than everything is working. Is there any one who can me explain this behaviour?

推荐答案

问题是，该单元格被选中，但 UICollectionView 对此一无所知.对 UICollectionView 的额外调用解决了这个问题:

The issue is, that the cell is selected, but the UICollectionView does not know anything about it. An extra call for the UICollectionView solves the problem:

[collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone]; 

完整代码:

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
    cell.selected = YES;
    [collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
    return cell;
}

我保留这个问题是为了帮助可能面临同样问题的人.

I keep the question to help someone who may face the same problem.

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