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];
}

Distended

I strongly suspect that you are using a UIAlertController somewhere and don't realise it and don't intend to. Set breakpoints where you present UIAlertControllers and see what happens – Chemesh

I had a breakpoint set on + [UIAlertController alertControllerWithTitle:message:preferredStyle:] and there were none. I did later create an alert and the breakpoint did work. – Distended

do you override dealloc anywhere? can you post more code? – Roustabout

Many of the classes have a dealloc method to deregister from notifications. I'll add that above. – Distended

Hey, I'm encounting this situation now. Did u fix this problem already? how? – Einberger

@Einberger i wish, but no, still unresolved. vote this question up and i'll add a bounty tomorrow – Distended

same error here... And I don't have any UIAlertController instantiated... – Listel

Totally off topic, but... If all your method -deregisterNotificationHandlers does is just call +[NSNotificationCenter removeObserver:], perhaps you can do that directly in -dealloc and cut a superfluous method... – Leucotomy

Are you assigning a UIAlertViewController to a property of the view controller? If so, in the alert's action handlers, do you happen to have any strong references which should really be weak? – Zimmer

@Zimmer I do not – Distended

@Distended Can you check whether your references are strong where they should be? Could something be released too quickly? – Acquisition

Also seeing this same issue – Amphicoelous

Will this cause app review to reject? What about for testflight? – Diphosgene

I was also experiencing this without having any UIAlertControllers in my application. However, my push was being initiated by resuming user activity via application:continueUserActivity:restorationHandler: in my AppDelegate. I had not overriden application:willContinueUserActivityWithType:; according to this post, this can lead to UIAlertControllers being shown, and hence the error message. Overriding the application:willContinueUserActivityWithType: function solves the problem for me. – Kerek

Answer 1

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.

Distended

In my case also same error shown in console on the view contain Mapbox MGLMapView – Referential

Answer 2

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!

Rahn

Thanks, but I have no class variables of UIAlertView or UIAlertViewController. – Distended

@picciano, Check again somewhere where your defining before view loads or something... this message is caused by that ! try to search throw the project and disable any alert your using ! i had this error just days ago and i know what its about ! it happens when you push a controller to where the alert is declared. – Rahn

Thanks. Wow, this is counterintuitive. I defined an UIAlertView in a local variable and then didn't present it in some cases. I couldn't find out what was wrong, saved my day ;) – Platinic

In my case the problem was an UIActionSheet as instance variable. +1 – Umbrageous

In my case it was the 3rd party bundle "Siren" that instantiated a UIAlertController without presenting it. – Ace

For me, it's not defined anywhere, I am not using any third party libs. I can't find what's wrong. var message:String? if somthn message = "a" if message { let alert = UIAlertController(title: "Game Over", message: message, preferredStyle: UIAlertControllerStyle.Alert) let action = UIAlertAction(title: "OK", style: UIAlertActionStyle.Destructive, handler:nil) alert.addAction(action) self.presentViewController(alert, animated: true, completion: nil)}} – Marielamariele

@NikitaP , it might be that you are presenting the alert while removing view or view controller ! I suggest you get top view controller (you will find that in stackoverflow) and then present the alert on that top controller ! – Rahn

@Rahn Thanks, I found the issue, it was while setting the boolean, I was changing this in between, which was making this call twice, before the first one gets over. – Marielamariele

I had forgotten writing the line self.presentViewController(alert, animated: true, completion: nil). Writing it solved the problem. Thanks. – Lucky

Answer 3

We had the same issue with UIAlertController.

let alert = UIAlertController(title: "", message: "", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: {(action : UIAlertAction!) in
                //some actions
                              } ))

I had forgot adding the following line. Below line solved the problem.

self.presentViewController(alert, animated: true, completion: nil)

Communist

Answer 4

I solved this by moving some of my code to viewDidAppear. If I used UIAlertController, it would cause the same problem you mentioned and would not be displayed, and I solved it the same way.

Let me know if that doesn't work!

Warnke

Thanks, but I am not instantiating any UIAlertController instances yet this error is logged to the console. – Distended

Yes, it doesn't just pertain to UIAlertController. What happens if you move all your view's initialization code to viewDidAppear? – Warnke

Answer 5

In my case, in Swift 3, I had missed the code below after adding the action

presentViewController(theAlert, animated: true, completion: nil)

So, the working code is as below

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {

     if (editingStyle == UITableViewCellEditingStyle.Delete) {

        let title = "Delete ????"
        let message = "Are you sure you want to delete this item?"

        let theAlert = UIAlertController(title: title,
                                   message: message,
                                   preferredStyle: .ActionSheet)

     let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel, handler: nil)
     theAlert.addAction(cancelAction)

     let onDelete = UIAlertAction(title: "Delete", style: .Destructive, handler: { (action) -> Void in
     self.items.removeAtIndex(indexPath.row)
     self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)

     })
     theAlert.addAction(onDelete)
        presentViewController(theAlert, animated: true, completion: nil)
     }
     }

//Note I was using a sample array

var items = ["iPhone", "iPad", "Mac"]

Newby

Swift 4 - use - present(controller, animated: true, completion: nil) – Bemire

Answer 6

I had the same issue, when I tried to remove a "frame" observer on my view in a UIViewController subclass. I solved this issue by wrapping the removeObserver in a isViewLoaded(). What exactly are you observing?

Bardwell

Thanks, but I am not using frame observers. – Distended

Answer 7

I had this problem by not having a navigationController... I know it sounds obvious but jumping about in various projects this one didn't have a UINavigationControllerto hand.... so others coming here you might want to NSLog your nav controller just for sanity too...

Prohibit