UICollectionView custom layout for reorder.

1 Xcode 11.3, swift 4.2 or above. 2 Implement UICollectionView and custom layout that displays folders and files. 3 Users can reorder an item by long tap on it, just implement UI, don’t need to reorder the real folders and files. 4 When the user drags a file over a folder, the folder zooms in, and the file will move into the folder if the tap gesture ends. 5 Smooth animations, flickering is not acceptable.