UIScrollView pan with 1 finger when zoomed in

Question

I got a scrollView with some sub views added to it. Scrolling and zooming works fine.

What I would like to is when the scrollView is zoomed in, alter the behavior of the 1 finger touch to pan instead of scroll.

Right now if you are zoomed in and move around with 1 finger you can only scroll the zoomed in content. With two fingers you can pan around. This is the behaviour I would like to change.

I haven't found any solution to this issue and I don't really have any ideas except trying to alter the minimum and maximum touches required but it doesn't seem to work.

func scrollViewDidZoom(_ scrollView: UIScrollView) {
    scrollView.panGestureRecognizer.maximumNumberOfTouches = 1
}

func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
    if scale == 1 {
        scrollView.panGestureRecognizer.maximumNumberOfTouches = 2
    }
}

Answer 1

I realized the issue I had was that each subview had their own scrollView (in my case my subviews wkWebViews). They were handling their own zoom even though I was trying to zoom from the UIScrollView.

I took these steps to solve this issue.

MyClass: UIViewController, UIScrollViewDelegate {

  // This view should handle the zooming 
  @IBOutlet var scrollView: UIScrollView!

  // .. and this view will contain all subviews to be zoomed
  @IBOutlet var wrapper: UIView!

  override func viewDidLoad() {
    super.viewDidLoad()

    self.scrollView.delegate = self
    self.addSViewsToScrollView()
  }

  func addViewsToScrollView () {

    // MARK: - Step 1 
    // .. set wkWebView scrollview maximum and minimum zoom scale to 1.

    let myArray: [WkWebView]? = [WkWebView(),WkWebView(),WkWebView()] 

    for view in myArray {
      wkWebView.scrollView.maximumZoomScale = 1
      wkWebView.scrollView.minimumZoomScale = 1
      wkWebView.isUserInteractionEnabled = false // This is key otherwise it wont work
      wkWebView.scrollView.isUserInteractionEnabled = false // .. this aswell
    }

    // MARK: - Step 2
    // .. add all views to a wrapper view

    for view in myArray {
      self.wrapperView.addSubview(view)
    }

  }

  func viewForZooming(in scrollView: UIScrollView) -> UIView? {
    return self.wrapper
  }
}

By returning a single view the panning in the zoomed in state works fine. Also the wkWebView scrollViews do not interfere with the zooming anymore.