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iosobjective-cuiviewcontrolleruinavigationcontrollercatransition

Can't pop viewController

I'm using this code to show a UIViewController:

CATransition *transition = [CATransition animation];
transition.duration = 0.f;
transition.type = kCATransitionFade;
[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController pushViewController:newVC animated:NO];

and the viewController is displayed correctly. Then I'm using this code to prepare an animation (Used to animate the pop):

CATransition *transition = [CATransition animation];
transition.duration = 0.f;
transition.type = kCATransitionFade;
[self.navigationController.view.layer addAnimation:transition forKey:nil];

However, neither of these lines will pop it:

[self.navigationController popViewControllerAnimated:NO];
[self.navigationController popToRootViewControllerAnimated:NO];

What could be the issue? Logging the navigation stack displays both the correct UIViewControllers:

NSLog(@"%@", self.navigationController.viewControllers);
Solution

  • Ok, so this is embarrassing.

    I was running the push call in the viewDidAppear:animated:, and I had forgotten to implement a check if we had already pushed. So when I popped the new UIViewController, the viewDidAppear:animated re-pushed the new VC again. I also set the it to animate:NO and removed the custom transition, causing the pop and re-push to happen basically instantaneously.

    I discovered this by putting a breakpoint at the pop message, and noticed the simulator displayed the root UIViewController for a fraction of a second.