I recently moved a code base from using AQGridView — a third party library — to UICollectionView. I have nothing against third party components but I’m a big fan of minimising dependencies and reducing the amount of code that need to be understood. In this case I managed to remove about 5000 lines of code from the project. Switching to the UIKit version made sense on both counts.
Both components do more or less the same thing and their APIs fortunately look pretty similar. (UICollectionView can be coerced into doing a lot more but we just need it for a simple grid.) Most of the changes are just renaming methods; I was surprised how little new code needed to be written.