jamztang/CSStickyHeaderFlowLayout — pull request #20 by Xyand (2014-08-17 14:31:20+00:00)
Title: Fix CollectionView zIndex issue when cells travel between sections

UICollectionView doesn't handle zIndex very well during transitions. It caused some of cells to be shown above sticky header when these cells moved from one section to another.

http://stackoverflow.com/questions/12659301/uicollectionview-setlayoutanimated-not-preserving-zindex