ios – 使用具有UIDynamics的UICollectionViewFlowLayout [UICollectionView performBatchUpdates：]

好的基本概述我有一个UICollectionView,我需要支持通过performBatchupdates：方法添加和删除项目.如果我使用标准的UICollectionViewFlowLayout,它工作正常.

但是,当我尝试使用由UIDynamicAnimator驱动的UICollectionViewFlowLayout时,一旦我调用performBatchChanges,我就会遇到崩溃.

在我的自定义UICollectionViewFlowLayout类中,prepareForCollectionViewupdates：方法从未被调用.我使用的自定义UICollectionViewFlowLayout基于this sample.

崩溃后的控制台输出是…

*** Assertion failure in -[UICollectionViewData layoutAttributesForItemATindexPath:],/sourceCache/UIKit/UIKit-2903.23/UICollectionViewData.m:581
*** TerminaTing app due to uncaught exception 'NSInternalInconsistencyException',reason: 'no UICollectionViewLayoutAttributes instance for -layoutAttributesForItemATindexPath: <NSIndexPath: 0xc000000000028096> {length = 2,path = 2 - 5}'
*** First throw call stack:
libc++abi.dylib: terminaTing with uncaught exception of type NSException

有任何想法吗？

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemATindexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *layoutAttributes = [self.dynamicAnimator layoutAttributesForCellATindexPath:indexPath];
    if(!layoutAttributes) {
        layoutAttributes = [super layoutAttributesForItemATindexPath:indexPath];
    }
    return layoutAttributes;
}