How to know if the VC got popped FULLY using interactivePopGestureRecognizer (swipe to go back)

Question

I am using a custom Left Menu Controller which can be opened by UIPanGestureRecognizer when the UINavigationController is only at it's Top-Level. If some UIViewController is pushed onto the stack, I want the interactivePopGestureRecognizer to work as expected and pop the VC when user swipes from left-to-right instead of the Left-Menu being opened. To achieve this, i sub-classed the UINavigationController as follows:

- (void)viewDidLoad {
    [super viewDidLoad];
    //[self.interactivePopGestureRecognizer setDelegate:nil];
    [self.view addGestureRecognizer:[self createPanGestureRecognizer]];
}

- (UIPanGestureRecognizer *) createPanGestureRecognizer {
    SGFPanGestureRecognizer * panRecognizer = [[SGFPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureRecognized:)];
    return panRecognizer;
}

-(void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    if(self.viewControllers.count == 1)
        if(self.view.gestureRecognizers && self.view.gestureRecognizers.count>0)
            for (UIGestureRecognizer * recog in self.view.gestureRecognizers)
            {
                if([recog isKindOfClass:[SGFPanGestureRecognizer class]]) {
                    [self.view removeGestureRecognizer:recog];
                    break;
                }
            }
    [super pushViewController:viewController animated:animated];
}

-(UIViewController *)popViewControllerAnimated:(BOOL)animated {
    UIViewController * vc = [super popViewControllerAnimated:animated];
    if(self.viewControllers.count == 1)
        [self.view addGestureRecognizer:[self createPanGestureRecognizer]];
    return vc;
}

Everything is working fine except one: When i am at a detailViewController and I swipe from left, the VC starts the "POP" animation which goes along my finger. If I leave the gesture too quick, the detailViewController doesn't really gets popped and rolls back the popping animation. However, this action fires the popViewControllerAnimated and my logic above becomes useless.

SUMMARY: So is there a way to understand if the swipe-to-back gesture is released too early to really pop the UINavigationController?