Attempting to load the view of a view controller while it is deallocating ... UIAlertController

Question

I am building with the release version of Xcode 7.0. No storyboards, just nib files.

I have a single UINavigationController created by the app delegate and initialize it with a view controller.

self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
UIViewController *viewController = [[TGMainViewController alloc] initWithNibName:nil bundle:nil];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];
self.navigationController.navigationBar.barStyle = UIBarStyleBlack;
self.navigationController.navigationBar.hidden = YES;
self.window.rootViewController = self.navigationController;
[self.window makeKeyAndVisible];

After navigating to a new view using:

TGRoutePreparationViewController *viewController = [[TGRoutePreparationViewController alloc] initWithNibName:nil bundle:nil];
[self.navigationController pushViewController:viewController animated:YES];

Then going back using:

[self.navigationController popViewControllerAnimated:YES];

I receive the following error:

Attempting to load the view of a view controller while it is deallocating is not allowed and may result in undefined behavior (<UIAlertController: 0x7b29a600>)

While I do use UIAlertControllers in the app, none are used or instantiated before receiving this error. This only happens when running under iOS 9.0. Running under iOS 8.4 produces no error. In all cases, the app appears to function normally and the navigation appears to be working.

I suspect the error is misleading, but how can I fix this?

Per @Nick, here is the dealloc method being used:

- (void)deregisterNotificationHandlers {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)dealloc {
    [self deregisterNotificationHandlers];
}

Answer 1

I had the same issue with my UIViewController where i was only declaring variable in my class let alert = UIAlertView() without using it yet, it was out of all the functions just inside the class as variable. by removing that solves the issue. so please check in your class if you have defined alert from UIAlertView or UIAlertViewController like that without using it or in the class variable!

Answer 2

I was finally able to track it down to a UIActionSheet class variable inside a third-party library, Mapbox GL.

I opened an issue with that dev team: https://github.com/mapbox/mapbox-gl-native/issues/2475

Partial credit (and an up vote and bounty) to @Aaoli for mentioning having a UIAlertView as a class variable.