Having two headers in UICollectionView? I've got a UICollectionView which uses the flow layout, which also has a header and footer: --------- | head | --------- | A | B | --------- | C | D | --------- | foot | --------- Occasionally, I'd like to have two headers, like so: --------- | head1 | --------- | head2 | --------- | A | B | --------- | C | D | --------- | foot | --------- I'm stuck on how t