Assertion Failure in UICollectionViewData indexPathForItemAtGlobalIndex

Question

I am using performBatchUpdates() to update my collection view, where I am doing a complete refresh, i.e. delete whatever was in it and re-insert everything.

Answer 1

This is the proper workaround to this crash:

Each of your supplementary views are associated with a certain index path. If you don't have a cell at that index path (initial load, you've deleted the row, etc), return a height of 0 for your supplementary view via your layout's delegate.

So, for a flow layout, implement UICollectionViewDelegateFlowLayout's

(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section

method (and the corresponding footer method, if you're using footers) with the following logic

if ( you-have-a-cell-at-the-row-for-this-section )
    return myNormalHeaderSize;
else return CGSizeMake( 0,0 );

Hope this helps!