On zoom, UIScrollview subviews not recognizing gesture

Question

I have a scrollview to which I have added an image view as a subview. The contentsize of the scrollview is same as the size of the imageview (width and height). There are two buttons outside the scrollview. When I click on either on them, a small rectangle view is added as a subview to the imageview. This rectangle view can be dragged anywhere on the imageview by the user after it has been added.

This works fine until I pinch to zoom the scrollview. In the viewForZoomingInScrollView: method, I return the imageview and the zooming works fine. But in the zoomed view when I try to drag around the rectangle view, it does not move. It does not recognize the pan gestures any more. Any idea why this is happening?

Thanks

Hetal

Answer 1

Following up to your last comment, I'd suggest to try the following:

In your viewDidLoad method add this:

for (UIGestureRecognizer *gr in self.scrollView.gestureRecognizers) {
    if ([gr isKindOfClass:[UIPanGestureRecognizer class]])
    {
        [gr requireGestureRecognizerToFail:self.dragGR];
    }
}

where dragView is your rectangleView.

The following is probably not necessary for the above to work, but it might be good practice to clean up the view hierarchy anyway:

Add a plain UIView as superview of your image view with the same frame and add the rectangle view as subview of that new view. In your viewForZoomingInScrollView: return that new view. As I said in the comments I don't think adding subviews to UIImageViews is considered good practice. But maybe that's just my opinion :)

Answer 2

这也应该工作，并且更加简洁：

[self.scrollView.panGestureRecognizer requireGestureRecognizerToFail:self.myPanRecognizer];