How can I detect the scroll direction from the UICollectionView?

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
}

Try this:

Add this somewhere in you header:

@property (nonatomic) CGFloat lastContentOffset;

Then override the scrollViewDidScroll: method:

#pragma mark - UIScrollViewDelegate

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (self.lastContentOffset > scrollView.contentOffset.y)
    {
        NSLog(@"Scrolling Up");
    }
    else if (self.lastContentOffset < scrollView.contentOffset.y)
    {
        NSLog(@"Scrolling Down");
    }

    self.lastContentOffset = scrollView.contentOffset.y;
}

Found in Finding the direction of scrolling in a UIScrollView?

I was trying to find a way to detect if the user is mostly trying to pull vertically or horizontally the scrollView. I give you my solution, I hope it can be useful to anyone :

CGPoint _lastContentOffset;

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    _lastContentOffset = scrollView.contentOffset;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    if (ABS(_lastContentOffset.x - scrollView.contentOffset.x) < ABS(_lastContentOffset.y - scrollView.contentOffset.y)) {
        NSLog(@"Scrolled Vertically");
    } else {
        NSLog(@"Scrolled Horizontally");
    }

}

This work find for me and I use this to avoid the scrollView to move horizontally when scrolling vertically and opposite.

this is the best way to get scroll direction, hope this helps you

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {

    CGPoint targetPoint = *targetContentOffset;
    CGPoint currentPoint = scrollView.contentOffset;

    if (targetPoint.y > currentPoint.y) {
        NSLog(@"up");
    }
    else {
        NSLog(@"down");
    }
}