iOS 10中的UICollectionView对齐单元格

Question

I have a collection view that used to look like this (iOS 9-):

As of iOS 10 however, that exact same untouched collection view is displaying like this:

No constraints or anything really have been changed from iOS 9 to iOS 10. I simply cannot figure out what the issue is. If it helps, the only constraints on this collection view are 0 spacing stuck to top, left, right and bottom:

Any help is greatly appreciated.

Answer 1

The issue was I forgot to add constraints for the containing view. Fixed.