To intercept the back swipe gesture you can set self
as the delegate of the gesture (<UIGestureRecognizerDelegate>
) and then return YES or NO from gestureRecognizerShouldBegin
based on unsaved changes:
// in viewDidLoad
self.navigationController.interactivePopGestureRecognizer.delegate = self;
// ...
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
if ([gestureRecognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]]) {
if (self.dirty) {
// ... alert
return NO;
} else
return YES;
} else
return YES;
}
In the alert you can ask to the user if she want to go back anyway and, in that case, pop the controller in alertView clickedButtonAtIndex:
Hope this is of some help.