CODEWITHSUNDEEP
iosswiftuiviewuicollectionviewuiswipegesturerecognizer
Eswar
Eswar

Reputation: 199

How to know that when the user swipe up / down?

I have UICollectionView in my ViewController (Please check below attached image for view hierarchy). How can we detect when the user swipes up or down?

It doesn't matter if we add gesture recognizer to UIView or UICollectionView. I just want to know the swipe gesture.

View Hierarchy

I've tried adding gesture recognizer to UIView and UICollectionView by using codes in stack overflow. But none of them satisfied my requirement.

Thanks in advance.

Upvotes: 0

Views: 960

Answers (1)

PGDev
PGDev

Reputation: 24341

Since collectionView is a basically a scrollView, use scrollViewDidScroll(_:) method to identify the scrolling direction of the collectionView. 

private var lastContentOffset: CGFloat = 0.0

In the above code, lastContentOffset keep track of the previous contentOffset of the collectionView while scrolling.

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if (scrollView.contentOffset.y < self.lastContentOffset) {
        //Scrolling up
    }
    else if (scrollView.contentOffset.y > self.lastContentOffset) {
        //Scrolling down
    }
    self.lastContentOffset = scrollView.contentOffset.y
}

Don't forget to conform to UICollectionViewDelegate protocol.

Also, there is no need for adding any separate gestureRecognizer. UICollectionView being a UIScrollView will handle it on its own.

Upvotes: 1

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