Assertion failure in -[UICollectionViewData validateLayoutInRect:],

UICollection 报错

 Assertion failure in -[UICollectionViewData validateLayoutInRect:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3512.30.14/UICollectionViewData.m:399
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UICollectionView received layout attributes for a cell with an index path that does not exist: 0xc000000000000016> {length = 2, path = 0 - 0}'

描述一下场景:

我使用collectionView 创建了一个瀑布流效果, 并且缓存了数据. 当我进入这个界面时, 我会先加载缓存数据, 再加载网络数据. 我怀疑报这个错误的原因是: 我加载网络数据后. [collection reloaddata] . 但是这时候 layout 可能没有更新

解决办法:

在网络上找了一些资料

-(NSInteger )numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
    [collectionView.collectionViewLayout invalidateLayout];
    return 1;
}

参考资料

http://stackoverflow.com/questions/18339030/uicollectionview-assertion-error-on-stale-data

It depends on whether your layout changes too. If your data change is just appending to the end, then you will not need to - if data is inserted above/within your current scroll position, then your cells for those index paths will move, and hence the layout is invalid