When I drag & drop a cell in a UICollectionView, sometimes, this crash happens:
Assertion failure in -[_UICollectionViewDragAndDropController _beginDragAndDropInsertingItemAtIndexPath:], _UICollectionViewDragAndDropController.m:615
Shadow insert is nil. File a bug on UICollectionView!
What can I do to prevent it from happening?
Make sure to update your cells properly (using reloadData/insertItems/reloadItems/deleteItems/reloadSections) to reflect any changes in the data source.