How to focus a UICollectionViewCell that has been focused?

Question

What I want to achieve is very simple: every time the user focuses the collection view cell, I want to make the focused cell horizontally centered. It seems my current approach does not work at all.

    func collectionView(collectionView: UICollectionView, didUpdateFocusInContext context: UICollectionViewFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
        guard collectionView === self.categoryCollectionView else {
            return
        }
        guard let indexPath = context.nextFocusedIndexPath else {
            return
        }

        collectionView.scrollToItemAtIndexPath(indexPath, atScrollPosition: .CenteredHorizontally, animated: true)
    }

It is odd that the collection view ignores any attempt to scroll anywhere. For testing purposes, I changed the index path to the last index path of the element in the collection view, but it only works if the collection view is displayed for the first time.

Answer 1

The trick is to make sure you set UICollectionView scrollEnabled = false.

override func didUpdateFocusInContext(context: UIFocusUpdateContext, 
  withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
    if let focusedView = context.nextFocusedView as? UITableViewCell {
      collectionView.scrollEnabled = false
      let indexPath = collectionView.indexPathForCell(focusedView)!
      collectionView.scrollToItemAtIndexPath(indexPath, atScrollPosition: .CenteredHorizontally, animated: true)
    }
}

Answer 2

, - AirBnB Focus, . ( GitHub) UIButton, , , CollectionView.

, !