Can a UIWebView in a UINavigationController allow the iOS 7 swipe-to-pop built-in gesture to be recognized?

Question

I want the normal UINavigationController swipe-back-to-pop gesture to work on a view controller that is basically a UIWebView browser. By default it seems that the UIWebView doesn't allow the UINavigationController swipe-back gesture to be recognized.

If I set the UIWebView.delegate to my view controller, and add the below method, it will recognize the UINavigationController's back-swipe correctly.

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    return YES;
}

But after completing that gesture (which pops the UIWebView's view controller), when I do another gesture it crashes. (Stack trace below.) And by "other gesture" I mean simply scrolling a UIWebView on the view controller I popped to after the swipe.

Is the problem that the always YES return value is messing up the normal interaction of the UIWebView gestures? It seems like I want to only allow the navigation gesture to always be YES, but then I want the webview gestures to do whatever they do normally, but I can't just call [super gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:] to get that behavior. Frankly I was surprised that the UIWebView delegate was being sent the gesture callbacks at all.

Thread 1, Queue : com.apple.main-thread
#0  0x3a80cb66 in objc_msgSend ()
#1  0x32e23f9a in -[UIGestureRecognizer _delegateCanPreventGestureRecognizer:] ()
#2  0x32cce418 in -[UIGestureRecognizer _isExcludedByGesture:] ()
#3  0x32c9410e in _UIGestureRecognizerUpdate ()
#4  0x32ccd1b4 in -[UIWindow _sendGesturesForEvent:] ()
#5  0x32cccb62 in -[UIWindow sendEvent:] ()
#6  0x32ca1f58 in -[UIApplication sendEvent:] ()
#7  0x32ca0746 in _UIApplicationHandleEventQueue ()
#8  0x304e2f26 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#9  0x304e23ee in __CFRunLoopDoSources0 ()
#10 0x304e0bde in __CFRunLoopRun ()
#11 0x3044b540 in CFRunLoopRunSpecific ()
#12 0x3044b322 in CFRunLoopRunInMode ()
#13 0x351822ea in GSEventRunModal ()
#14 0x32d021e4 in UIApplicationMain ()
#15 0x000df478 in main at /path/to/main.m:17
#16 0x000df398 in start ()

m8labs m8labs · Accepted Answer · 2014-04-22T19:21:43

I just faced the same problem (but I had regular UIViewController instead - MWPhotoBrowser - that in some reason also blocked this system back gesture) and I solved it by setting

self.navigationController.interactivePopGestureRecognizer.delegate = nil;

in viewWillDisappear: handler. Hope it helps.

Can a UIWebView in a UINavigationController allow the iOS 7 swipe-to-pop built-in gesture to be recognized?

1 Answers