TVOS , 检测 indexPath FocusUpdate

TVOS , detect indexPath FocusUpdate

如何使用此代码获取和检测 collectionView 中聚焦的项目的 indexPath 或?

- (void)didUpdateFocusInContext:(UIFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator
{}

使用didUpdateFocusInContect - UICollectionViewDelegate

func collectionView(collectionView: UICollectionView, didUpdateFocusInContext context: UICollectionViewFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
     // indexPath that is going to be focused
     print(context.nextFocusedIndexPath)

     // indexPath that is going to lose focus
     print(context.previouslyFocusedIndexPath)
}