Implementing something as big and complex as a custom
UICollectionViewLayout looks like quite the challenge for most people. Creating a custom layout involves calculating the position for each and every cell that your collection view will display. You will have to make sure that your code does this as fast and efficiently as possible because your layout code will directly influence the performance of the entire collection view. Luckily, the documentation for implementing a custom layout is pretty good.
If you look at the documentation for
UICollectionViewLayout, you can read about its role in a
UICollectionView. This information shows that a custom layout requires you to handle layout for cells, supplementary ...