Turn off Zooming in UIScrollView

Question

Does anyone know a way to temporarily turn off zooming when using a UIScrollView?

I see that you can disable scrolling using the following:

self.scrollView.scrollEnabled = false;

but I'm not seeing a similar command for zooming. Any thoughts?

Answer 1

If you want to disable the user's ability to zoom through gestures then in iOS 5 and above you can disable the pinch gesture. This still allows you to control the scroll view from code...

scrollView.pinchGestureRecognizer.enabled = NO;

similarly for pan...

scrollView.panGestureRecognizer.enabled = NO;

This must be called in - (void)viewDidAppear:(BOOL)animated or later as otherwise the system resets it to enabled.

Answer 2

Swift 3 Version:

func lockScrollViewZooming() {
    scrollView.minimumZoomScale = 1.0
    scrollView.minimumZoomScale = 1.0
    scrollView.bounces = false
    scrollView.bouncesZoom = false

    // Also, if you have double tap recognizer,
    // remember to remove it
    scrollView.removeGestureRecognizer(doubleTapGestureRecognizer)
}

func unlockScrollViewZooming() {
    scrollView.minimumZoomScale = 1.0
    scrollView.maximumZoomScale = 4.0
    scrollView.bounces = true
    scrollView.bouncesZoom = true

    // Also, if you have double tap recognizer,
    // remember to add it
    scrollView.removeGestureRecognizer(doubleTapGestureRecognizer)
}

Note that doubleTapGestureRecognizer should be an instance variable. It should be similar to:

private lazy var doubleTapGestureRecognizer: UITapGestureRecognizer = {
    let doubleTapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleDoubleTap(_:)))
    doubleTapGestureRecognizer.numberOfTapsRequired = 2
    doubleTapGestureRecognizer.delegate = self

    return doubleTapGestureRecognizer
}()

@objc private func handleDoubleTap(_ recognizer: UITapGestureRecognizer) {
    //scrollView.setZoomScale((scrollView.zoomScale > scrollView.minimumZoomScale) ? scrollView.minimumZoomScale : scrollView.maximumZoomScale, animated: true)

    if scrollView.zoomScale > scrollView.minimumZoomScale {
        scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)
    } else {
        let touchLocation = recognizer.location(in: recognizer.view)
        scrollView.zoom(to: CGRect(origin: touchLocation, size: CGSize(width: 22.0, height: 20.0)), animated: true)
    }
}

Answer 3

I have tried setting minimumZoomScale and maximumZoomScale properties of UIScrollView to 1 or isMultipleTouchEnabled property of UIView to false or return nil from viewForZooming(in:) of UIScrollViewDelegate but none worked. In my case, after several trial and error, the following works in my case [Tested on iOS 10.3]:

class MyViewController: UIViewController {
   var webView: WKWebView?

   override viewDidLoad() {
      super.viewDidLoad()

      //...
      self.webView.scrollView.delegate = self
      //...
   }
}

extension MyViewController: UIScrollViewDelegate { 
   func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?) {
      scrollView.pinchGestureRecognizer?.isEnabled = false
   }
}