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这曾经在 iOS 6 中工作，但在 iOS 7 中失败

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:1 inSection:0];
    [self.collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
    NSArray *selectedPaths = self.collectionView.indexPathsForSelectedItems;
    NSAssert(selectedPaths.count == 1, @"viewWillAppear - Should be 1 but is %d", selectedPaths.count);
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSArray *selectedPaths = collectionView.indexPathsForSelectedItems;
    NSAssert(selectedPaths.count == 1, @"cellForItemAtIndexPath - Should be 1 but is %d", selectedPaths.count);
}

cellForItemAtIndexPath 中的断言失败：

*由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“cellForItemAtIndexPath - 应为 1 但为 0”

我使用 selectItemAtIndexPath:indexPath API 在 vi​​ewWillAppear 中选择了一个项目，但是当调用 cellForItemAtIndexPath 时，collectionView 已经忘记选择了任何内容。知道为什么吗？

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1 回答 1

3

嗬！

UICollectionViewController.clearsSelectionOnViewWillAppear
于 2013-10-08T02:51:47.540 回答