Even though UICollectionView is incredibly flexible and versatile, trivial things are sometimes difficult to accomplish. UITableView, on the other hand, has more configuration options, but it is harder to customize. Sticky section headers, for example, are built into table views. Adding them to a collection view requires a bit of extra work.
If your project targets iOS 9 or higher, then you are in luck. Since iOS 9, the UICollectionViewFlowLayout class has two properties, sectionHeadersPinToVisibleBounds and sectionFootersPinToVisibleBounds, that make it very easy to make section headers and section footers sticky. It is no coincidence that these properties are members of the UICollectionViewFlowLayout class. It is UICollectionViewFlowLayout we need to subclass to add sticky section headers.
Read this article on the blog.