What I mean is using the native UICollectionViewDataSource methods that can be overridden to display an index view: indexTitles(for:) and collectionView(_:indexPathForIndexTitle:at:). These are supported since iOS 14. See "Configuring an Index" here: https://developer.apple.com/documentation/uikit/uicollectionviewdatasource

Thank you for your suggestion. Yes, this is exactly what we did with the previous third-party view, using setContentOffset() to scroll the view to the correct section header after receiving the selected section in a callback. However, with the built-in approach, I don't know of any way we could be notified when the user changes to a different section via the index, i.e. we wouldn't know when to apply the scroll offset.