UIPinchGestureRecognizer is firing twice

Question

I am adding UIPinchGestureRecognizer to a scrollView which shows images. On pinch, I am presenting a new view.

var pinch = UIPinchGestureRecognizer(target: self, action: "showFullScreen:")
self.scrollView.addGestureRecognizer(pinch)

The showFullScreen function:

func showFullScreen(sender:UITapGestureRecognizer) {     
    presentViewController(photoBro, animated: true, completion: nil)
}

But when I pinch on scrollView, showFullScreen is called twice because of which the following error comes:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present modally an active controller

I was searching for solution, and they suggest to remove the pinchGesture, but I want to keep the gestureRecognizer, so that users can still pinch to enter full screen.

What can I do to ensure that showFullScreen is called only once for one pinch?

Answer 1

try this:

  func showFullScreen(sender:UITapGestureRecognizer) {     
     if(sender.state == UIGestureRecognizerState.Ended) {
         presentViewController(photoBro, animated: true, completion: nil)
     }    
  }