In the latest version we implemented UIGestureRecognizerDelegates internally and assigned one to all our gesture recognizers.
So the crash you are seeing is caused when you override our internal delegates.
To prevent the crash, you can replace your gesture recognizer loop with the following code:
chart.gestureManager.radialTapGesture.enabled = NO;
chart.gestureManager.doubleTapGesture.delegate = self;
chart.gestureManager.singleTapGesture.delegate = self;
However, can I ask what you are using the gesture delegate for?
As I want to make sure the above code is the most robust solution.