CODEWITHSUNDEEP
iosswiftxcodeoptimizationuiscrollview
user4806509
user4806509

Reputation: 3011

scrollViewDidEndZooming not called while zooming in a UIScrollView

This could possibly be an Xcode bug? I have an UIImage inside a UIScrollView done programatically in code. The user can zoom into the image using the zoom gesture or double tapping the image. This part all works fine.

Next, I am trying to detect when the scroll view has finished zooming after a zoom gesture or double tap using the below function scrollViewDidEndZooming. However, scrollViewDidEndZooming never gets called, and doesn't print the line I just finished zooming!

Code not working:

func scrollViewDidEndZooming(scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
    print("I just finished zooming!")
}

Question:

What might be going on here, why isn't scrollViewDidEndZooming(...) getting called?

Note: I've referred to the below document with no luck. https://developer.apple.com/reference/uikit/uiscrollviewdelegate/1619407-scrollviewdidendzooming

Complete code:

class ScrollViewController: UIViewController, UIScrollViewDelegate {
    var scrollView: UIScrollView!
    var imageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        imageView = UIImageView(image: UIImage(named: "image.png"))

        scrollView = UIScrollView(frame: view.bounds)
        scrollView.backgroundColor = UIColor.blackColor()
        scrollView.contentSize = imageView.bounds.size
        scrollView.autoresizingMask = [UIViewAutoresizing.FlexibleWidth, UIViewAutoresizing.FlexibleHeight]

        scrollView.contentOffset = CGPoint(x: 1000, y: 450)

        scrollView.addSubview(imageView)
        view.addSubview(scrollView)

        scrollView.delegate = self
        setZoomScale()
        setupGestureRecognizer()
    }

    func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
        return imageView
    }

    override func viewWillLayoutSubviews() {
        setZoomScale()
    }

    func setZoomScale() {
        let imageViewSize = imageView.bounds.size
        let scrollViewSize = scrollView.bounds.size
        let widthScale = scrollViewSize.width / imageViewSize.width
        let heightScale = scrollViewSize.height / imageViewSize.height

        scrollView.minimumZoomScale = min(widthScale, heightScale)
        scrollView.zoomScale = 1.0
    }

    func scrollViewDidZoom(scrollView: UIScrollView) {
        let imageViewSize = imageView.frame.size
        let scrollViewSize = scrollView.bounds.size
        let verticalPadding = imageViewSize.height < scrollViewSize.height ? (scrollViewSize.height - imageViewSize.height) / 2 : 0
        let horizontalPadding = imageViewSize.width < scrollViewSize.width ? (scrollViewSize.width - imageViewSize.width) / 2 : 0

        scrollView.contentInset = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
    }

    func scrollViewDidEndZooming(scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
        print("I just finished zooming!")
    }

    func setupGestureRecognizer() {
        let doubleTap = UITapGestureRecognizer(target: self, action: "handleDoubleTap:")
        doubleTap.numberOfTapsRequired = 2
        scrollView.addGestureRecognizer(doubleTap)
    }

    func handleDoubleTap(recognizer: UITapGestureRecognizer) {
        if (scrollView.zoomScale > scrollView.minimumZoomScale) {
            scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)
        } else {
            scrollView.setZoomScale(scrollView.maximumZoomScale, animated: true)
        }
    }
}

Upvotes: 3

Views: 2482

Answers (1)

Vasily Bodnarchuk
Vasily Bodnarchuk

Reputation: 25294

You make a small mistake. Try this code:

    func scrollViewDidEndZooming(scrollView: UIScrollView, withView view: UIView?, atScale scale: CGFloat) {
    print("I just finished zooming!")
}

Upvotes: 1

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