我正在使用performBatchUpdates()来更新我的集合视图,在其中进行完全刷新,即删除其中的所有内容并重新插入所有内容。批量更新是作为一个观察者的一部分完成的,该观察者附加到NSMutableArray
(bingDataItems
)上。
cellItems是包含将要插入到集合视图中的项目的数组。
以下是代码:
- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
cultARunner *_cultARunner = [cultARunner getInstance];
if ( [[_cultARunner bingDataItems] count] ) {
[self.collectionView reloadData];
[[self collectionView] performBatchUpdates: ^{
int itemSize = [cellItems count];
NSMutableArray *arrayWithIndexPaths = [NSMutableArray array];
// first delete the old stuff
if (itemSize == 0) {
[arrayWithIndexPaths addObject: [NSIndexPath indexPathForRow: 0 inSection: 0]];
}
else {
for( int i = 0; i < cellItems.count; i++ ) {
[arrayWithIndexPaths addObject:[NSIndexPath indexPathForRow:i inSection:0]];
}
}
[cellItems removeAllObjects];
if(itemSize) {
[self.collectionView deleteItemsAtIndexPaths:arrayWithIndexPaths];
}
// insert the new stuff
arrayWithIndexPaths = [NSMutableArray array];
cellItems = [_cultARunner bingDataItems];
if ([cellItems count] == 0) {
[arrayWithIndexPaths addObject: [NSIndexPath indexPathForRow: 0 inSection: 0]];
}
else {
for( int i = 0; i < [cellItems count]; i++ ) {
[arrayWithIndexPaths addObject:[NSIndexPath indexPathForRow:i inSection:0]];
}
}
[self.collectionView insertItemsAtIndexPaths:arrayWithIndexPaths];
}
completion:nil];
}
}
我遇到了这个错误,但并不总是出现(为什么?)
2012-12-16 13:17:59.789 [16807:19703] *** Assertion failure in -[UICollectionViewData indexPathForItemAtGlobalIndex:], /SourceCache/UIKit_Sim/UIKit-2372/UICollectionViewData.m:442
2012-12-16 13:17:59.790 [16807:19703] DEBUG: request for index path for global index 1342177227 when there are only 53 items in the collection view
我检查了唯一一个提到相同问题的线程:UICollectionView Assertion failure,但它不是很清楚,即在performBatchUpdates()
块中执行[collectionview reloadData]
是不可取的。
你有什么建议吗?