How to detect when a UIScrollView has finished scrolling

How to Detect When a UIScrollView Has Finished Scrolling 📜✅

Are you trying to figure out when a UIScrollView has completed scrolling? 🤔 The UIScrollViewDelegate has got two delegate methods - scrollViewDidScroll() and scrollViewDidEndScrollingAnimation(). Unfortunately, neither of these methods directly tell you when scrolling has completed. 😕 But fear not, we've got you covered with easy solutions to tackle this challenge! 💪

The Problem 🚩

Let's first understand the problem. The scrollViewDidScroll() method only notifies you that the scroll view did scroll, not that it has finished scrolling. On the other hand, scrollViewDidEndScrollingAnimation() seems to only fire when you programmatically move the scroll view and not when the user scrolls. 😞

The Solution 💡

To detect when a scroll view has completed scrolling, we can use a combination of delegate methods and UIScrollView properties.

Step 1: UIScrollViewDelegate

First, we need to set the scroll view's delegate and implement the scrollViewDidEndDragging(_:willDecelerate:) and scrollViewDidEndDecelerating() delegate methods.

scrollView.delegate = self

...

extension YourViewController: UIScrollViewDelegate {
    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if !decelerate {
            scrollViewDidFinishScrolling()
        }
    }
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        scrollViewDidFinishScrolling()
    }
    
    private func scrollViewDidFinishScrolling() {
        // Your code to handle scroll completion goes here
    }
}

Step 2: UIScrollView Properties

Next, we'll make use of the UIScrollView's isDragging and isDecelerating properties. These properties can help determine if the user-initiated scrolling has completed.

private func scrollViewDidFinishScrolling() {
    if !scrollView.isDragging && !scrollView.isDecelerating {
        // Your code to handle scroll completion goes here
    }
}

By checking if the scroll view is not dragging and not decelerating, we can confidently say that the scroll view has finished scrolling. Feel free to add your own code within the scrollViewDidFinishScrolling() method to handle scroll completion. 🎉

Call-to-Action 📣

And that's it! You now know how to detect when a UIScrollView has finished scrolling. Implement these steps in your project, and say goodbye to the frustration of not knowing when scrolling has completed! 😄

If you found this tutorial helpful, make sure to share it with others who might be facing similar challenges. Leave a comment below if you have any questions or suggestions for future blog posts. Happy coding! 💻💡🚀