Custom Storyboard Segue for viewing pop-ups?

I have a UINavigationController setting in my storyboard, and I created my own segue class, which you can see below, which nicely disappears between my views (and not the standard swamp push).

However, when I push this back button that the nav controller gave me, I get a push animation that I don't want, I want to use this fading! I also do not want transitions in both directions in my storyboard, as it was just confused.

Any help is much appreciated!

Custom fade segue:

-(void)perform
{
    __block UIViewController *sourceViewController = (UIViewController*)[self sourceViewController];
    __block UIViewController *destinationController = (UIViewController*)[self destinationViewController];

    [UIView transitionWithView:sourceViewController.navigationController.view duration:1.0 options:UIViewAnimationOptionTransitionCrossDissolve
                    animations:^
                    {
                        [sourceViewController.navigationController pushViewController:destinationController animated:NO];
                    }
                    completion:^(BOOL finished)
                    {
                        NSLog(@"Transition Completed");
                    }];
}

EDIT:

Perhaps I should simplify. How can I cross-blur between two view controllers in a UINavigationController that pushes and pops up, rather than the standard animation from left to right?

Thank.