UICollectionView - 尝试删除并重新加载相同的索引路径答案

【问题标题】：UICollectionView - attempt to delete and reload the same index pathUICollectionView - 尝试删除并重新加载相同的索引路径
【发布时间】：2016-01-12 17:15:21
【问题描述】：

这是PHPhotoLibraryObserver

- (void)photoLibraryDidChange:(PHChange *)changeInstance
{
    dispatch_async(dispatch_get_main_queue(), ^{
        PHFetchResultChangeDetails *collectionChanges = [changeInstance changeDetailsForFetchResult:self.assetsFetchResults];
        if (collectionChanges) {
            self.assetsFetchResults = [collectionChanges fetchResultAfterChanges];
            if (![collectionChanges hasIncrementalChanges] || [collectionChanges hasMoves]) {
                [self.collectionView reloadData];
            } else {
                // if we have incremental diffs, tell the collection view to animate insertions and deletions
                [self.collectionView performBatchUpdates:^{
                    NSIndexSet *changedIndexes = [collectionChanges changedIndexes];
                    if ([changedIndexes count]) {
                        [self.collectionView reloadItemsAtIndexPaths:[changedIndexes indexPathsFromIndexesWithSection:0]];
                    }
                    NSIndexSet *removedIndexes = [collectionChanges removedIndexes];
                    if ([removedIndexes count]) {
                        [self.collectionView deleteItemsAtIndexPaths:[removedIndexes indexPathsFromIndexesWithSection:0]];
                    }
                    NSIndexSet *insertedIndexes = [collectionChanges insertedIndexes];
                    if ([insertedIndexes count]) {
                        [self.collectionView insertItemsAtIndexPaths:[insertedIndexes indexPathsFromIndexesWithSection:0]];
                    }
                } completion:nil];
            }
        }
    });
}

删除其他应用中的照片后出现错误

这是一个错误：

由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“尝试删除并重新加载相同的索引路径（{length = 2, path = 0 - 0}）”

当我按如下方式对PHFetchResult 进行排序时。如上崩溃

PHFetchOptions *options = [[PHFetchOptions alloc] init];
options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
self.assetsFetchResults = [PHAsset fetchAssetsWithOptions:options];

当我将排序选项设置为零时。顺利

self.assetsFetchResults = [PHAsset fetchAssetsWithOptions:nil];

我不知道怎么了..

【问题讨论】：

标签： ios objective-c photos photokit

【解决方案1】：

在尝试重新加载之前过滤掉已删除的索引：

NSIndexSet *changedIndexes = [changeDetails changedIndexes];
NSMutableIndexSet *safeChangedIndexes = [[NSMutableIndexSet alloc] init];

// Filter out indexes that we've deleted
[changedIndexes enumerateIndexesUsingBlock:^(NSUInteger index, BOOL *stop)
{
    if (![removedIndexes containsIndex:index])
    {
        [safeChangedIndexes addIndex:index];
    }
}];
[self.collectionView reloadItemsAtIndexPaths:[safeChangedIndexes indexPathsFromIndexesWithSection:0]];

【讨论】：