How can I detect the scroll direction from the UICollectionView?

Question

I have a UICollectionView. I want to detect scroll direction. I have a two different animation style for scroll down and scroll up. So I must learn scroll direction.

Answer 1

Swift 4.2

private var lastContentOffset: CGFloat = 0
func scrollViewDidScroll(_ scrollView: UIScrollView) {

    if lastContentOffset > scrollView.contentOffset.y && lastContentOffset < scrollView.contentSize.height - scrollView.frame.height {
        // move up
        print("move up")
        originalHeight ()
    } else if lastContentOffset < scrollView.contentOffset.y && scrollView.contentOffset.y > 0 {
        // move down
        print("move down")
        minimizeHeaderView()
    }

    // update the new position acquired
    lastContentOffset = scrollView.contentOffset.y
}