iOS tableview how can I check if it is scrolling up or down
Like @maddy said in the comment of your question, you can check if your UITableView
is scrolling by using the UIScrollViewDelegate
and further more you could check which direction it scrolls to by using both scrollViewDidScroll
and scrollViewWillBeginDragging
functions
// we set a variable to hold the contentOffSet before scroll view scrolls
var lastContentOffset: CGFloat = 0
// this delegate is called when the scrollView (i.e your UITableView) will start scrolling
func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
self.lastContentOffset = scrollView.contentOffset.y
}
// while scrolling this delegate is being called so you may now check which direction your scrollView is being scrolled to
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if self.lastContentOffset < scrollView.contentOffset.y {
// did move up
} else if self.lastContentOffset > scrollView.contentOffset.y {
// did move down
} else {
// didn't move
}
}
Furthermore: You don't need to subclass your UIViewController
with UIScrollViewDelegate
if you've already subclassed your UIViewController
with UITableViewDelegate
because UITableViewDelegate
is already a subclass of UIScrollViewDelegate
You can implement scrollViewWillEndDragging
method:
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
if targetContentOffset.pointee.y < scrollView.contentOffset.y {
// it's going up
} else {
// it's going down
}
}