Disable automatic scroll in UICollectionView if user is scrolling - ios

Question

I have implemented an horizontal UICollectionView which scrolls automatically to the next cell after 3 seconds.
Everything works as expected, but I have ran into an issue.
Since the function fires automatically after 3 seconds, with a NSTimer it colides with the user's scroll if both occur at the same time.
Example:
User is scrolling left (backwards) at the same time the 3 second function fires, which will scroll to the right (next cell).
I am wondering if there's a way to let's say, disable the automatic scroll if the user himself is scrolling, and re-enable it after a few seconds, if the user stopped scrolling.
Here's my code:
override func viewDidLoad() {
super.viewDidLoad()
startTimer()
}
fileprivate func startTimer() {
Timer.scheduledTimer(timeInterval: 3.0, target: self, selector: #selector(scrollToNextCell), userInfo: nil, repeats: true)
}
#objc fileprivate func scrollToNextCell() {
let cellSize = CGSize(width: width, height: height)
let contentOffset = collectionView.contentOffset
if collectionView.contentSize.width <= collectionView.contentOffset.x + cellSize.width {
let rect = CGRect(x: 0, y: 0, width: cellSize.width, height: cellSize.height)
collectionView.scrollRectToVisible(rect, animated: false)
} else {
let rect = CGRect(x: contentOffset.x + cellSize.width, y: 0, width: cellSize.width, height: cellSize.height)
collectionView.scrollRectToVisible(rect, animated: true)
}
}
What's the best approach here?
Something along:
Collection view detects user scroll it disables the startTimer() function, then if the user stops scrolling, fires another function that waits Xn seconds to fire the startTimer() function again.
Then every time the user scrolls again, it disables again the startTimer() and the new function that enables the startTimer() if it was running.
How can I achieve this?

Answer 1

Make use of the UIScrollViewDelegate
// called on finger up as we are moving
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {
Invalidate Timer.
}
// called when scroll view grinds to a halt
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
Restart Timer.
}
Alternative Approach:
Make use if deceleratingproperty. It returns YES if user isn't dragging (touch up) but scroll view is still moving.
#objc fileprivate func scrollToNextCell() {
if (!collectionView.isDecelerating) {
//your code here
}
}