"Unbalanced calls to begin/end appearance transitions for DetailViewController" when pushing more than one detail view controller

Question

I have a view controller that contains a table view, the items in the table can be selected and a detail view controller duly created.

The items in the table represent items that can have a time based trigger associated with them and a local notification is scheduled for each item, if the app is in the foreground when a local notification expires then the detail view for the item is automatically displayed.

I have a problem that manifests when two notifications expire at the same time which results in the views not being displayed properly and in addition the console logs: "Unbalanced calls to begin/end appearance transitions for NNN" where NNN is my detail view controller.

The table view controller is created as follows:

 self.tableViewController = [[TableViewController alloc] initWithNibName:@"TableView" bundle:nil];
 UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:self.tableViewController];
 self.window.rootViewController = navController;

When a local notification expires and didReceiveLocalNotification: is invoked the app broadcasts a notification using NSNotifcationCenter postNotificationName: and to which the table view controller is listening for. When the table view controller receives that notification it creates the detail view controller and pushes it to the stack as:

[self.navigationController pushViewController:detailViewController animated:YES];

I read somewhere that there could be a problem if a view controller pushes another view controller when it itself is not on the top of the stack - so I thought this must be the problem, because when the table view controller receives the 2nd notification it will no longer be on the top of the navigation stack because it will have previously just pushed a detail view controller onto the stack when the first notification arrived.

So I changed the push code to this:

[[self.navigationController topViewController].navigationController pushViewController:detailController animated:YES];

But it made no difference.

So I next thought there could be a problem because the first detail view controller was not getting the chance to fully display before the 2nd view controller was pushed - so I changed my app's notification posting from using:

[[NSNotificationCenter defaultCenter] postNotificationName:

to

[[NSNotificationQueue defaultQueue] enqueueNotification: postingStyle:NSPostWhenIdle]

So that the pushes wouldn't occur within the same iteraction of the app loop. But that made no difference, nor did attempting to introduce a delay to the pushing of the detail view controlle:

double delayInSeconds = 0.1;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [[self.navigationController topViewController].navigationController     pushViewController:detailController animated:YES]; 
});

I've no idea what the problem is or what to try next, any ideas?

Got into a similar situation, found a fix: http://stackoverflow.com/questions/19500025/uinavigationcontroller-transition-animations-triggered-too-fast/19738292#19738292 — Matthew Quiros, Nov 02 '13 at 02:23

score 126 · Accepted Answer · edited Apr 17 '13 at 06:28

126

"The unbalanced calls to begin/end appearance transitions"

occurs when you try and display a new viewcontroller before the current view controller is finished displaying. You can reproduce it by navigating in viewWillAppear.

Basically you are trying to push two view controllers onto the stack at almost the same time. Suggest you maintain a queue in the tableview controller which maintains a list of the detail views which need displaying. Push one at a time on to the stack and check on exit from the current detail view whether there are any queued detail views which need displaying.

This kind of navigation is going to be confusing for the user. It may be better to consider making your detail view support multiple items.

edited Apr 17 '13 at 06:28

Chris Miles

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answered Feb 01 '12 at 00:08

railwayparade

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I noticed that when I was using postNofictionName: then the viewDidAppear: wasn't getting called for the first view before the 2nd one was being pushed. However after changing to use enqueNotification: viewDidAppear does get called before the 2nd view controller is pushed (because the pushes have changed from both occurring in the same run loop invocation to separate loop invocations). Therefore with this change hasn't the first view now finished appearing before the 2nd push occurs? Yet the problem still remains. – Gruntcakes Feb 01 '12 at 00:27
2

One of the most helpful answer from the other answers about this error. May I ask where you get the explanation from? I'd expect Apple docs to appear in Google when I was debugging but I couldn't find any docs on this. – Enrico Susatyo Apr 16 '13 at 12:14
In my case, I only have one view controller but I still get this error. Please check [this](https://stackoverflow.com/questions/74038000/unbalanced-calls-to-begin-end-appearance-transitions-for-iosscenedelegate-viewc) out. – NightFuryLxD Oct 12 '22 at 07:34
My problem was due to something else....different from what's been described above. Anyway, it's working now. – NightFuryLxD Oct 20 '22 at 06:40

score 12 · Answer 2 · edited May 12 '14 at 12:10

'Unbalanced calls to begin/end appearance transitions for '

Says an animation is started before the last related animation isnt done. So, are you popping any view controller before pushing the new one ? Or may be popping to root ? if yes try doing so without animation. i.e,

[self.navigationController popToRootViewControllerAnimated:NO];

And see if this resolves the issue, In my case this did the trick.

score 7 · Answer 3 · edited Nov 30 '13 at 02:43

"The unbalanced calls to begin/end appearance transitions" error occurs when you try and display a new viewcontroller before the current view controller is finished displaying.

So, you have to be sure you wont present a new VC until the first finishes its animations.

Use didShowViewController and willShowViewController to block presenting a new VC before the old one completes its animation. It's for backButtonAction who makes a popViewController with Animation: YES.

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    [self.myNavView.backButton addTarget:self action:@selector(backButtonAction) forControlEvents:UIControlEventTouchUpInside];
}

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    [self.myNavView.backButton removeTarget:self action:@selector(backButtonAction) forControlEvents:UIControlEventTouchUpInside];
}

"So, you have to be sure you wont present a new VC until the first finishes its animations." this lines works for me like magic.Saved my day. Thanks!!! — Akbari Dipali, Feb 20 '14 at 18:33

score 4 · Answer 4 · edited Nov 07 '21 at 04:58

In my case, I was implementing a custom container view controller, and I was getting the warning when swapping child view controllers, despite the fact that I was calling both beginAppearanceTransition(_:animated:) and endAppearanceTransition() on both the entering and the exiting view controllers.

I solved it by reordering the method calls for the entering view controller; from:

addChildViewController(newContent)
targetContainer.insertSubview(newContent.view, at: 0)

newContent.beginAppearanceTransition(true, animated: animated)
// Called AFTER adding subview

to:

// Called BEFORE adding subview 
newContent.beginAppearanceTransition(true, animated: animated)

addChildViewController(newContent)
targetContainer.insertSubview(newContent.view, at: 0)

score 3 · Answer 5 · answered Apr 05 '13 at 21:05

3

It can also happen when you try to pop a VC from the stack more than once. On my case, the method that popped the VC was mistakenly being called multiple times. Once I cleaned that up the issue went away.

answered Apr 05 '13 at 21:05

infinite-loop

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score 1 · Answer 6 · answered Apr 22 '14 at 11:41

Actually you need to wait till the push animation ends. So you can delegate UINavigationController and prevent pushing till the animation ends.

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated{
    waitNavigation = NO;
}


-(void)showGScreen:(id)gvc{

    if (!waitNavigation) {
        waitNavigation = YES;
        [_nav popToRootViewControllerAnimated:NO];
        [_nav pushViewController:gvc animated:YES];
    }
}

score 1 · Answer 7 · edited Nov 07 '21 at 04:58

1

You can add a breakpoint to

-[UIViewController _endAppearanceTransition:]

from where UIKit prints

"Unbalanced calls to begin/end appearance transitions for %@."

edited Nov 07 '21 at 04:58

Nimantha

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answered May 10 '19 at 15:13

Tim

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score 1 · Answer 8 · edited Nov 07 '21 at 04:57

1

As mentioned in above answers this error accuses when we try to push a view controller before the previous view controller is finish loading, so one solution is that try to push controller after it finish loading, i.e. move your push view controller code from viewWillAppear to viewDidAppear

edited Nov 07 '21 at 04:57

Nimantha

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answered Dec 02 '19 at 06:37

lakum vishal

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score 0 · Answer 9 · edited Feb 17 '14 at 11:54

0

Look at these overloads:

If they are empty, then remark them and rebuild.

- (void) beginAppearanceTransition:(BOOL) isAppearing animated:(BOOL)animated {}
- (void) becomeActive:(NSNotification *) notification {}

edited Feb 17 '14 at 11:54

Rick Hoving

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answered Feb 17 '14 at 11:37

Ioannis Kousis

1

score 0 · Answer 10 · answered Jun 18 '18 at 10:07

In my case the problem is that I am presenting a viewController (alert) on an already presented viewController (full screen sheet). UIKit walks up the viewController parent chain but not the presenting chain so there is a mismatch when reaching the presented and the window root view controller. Manually calling beginAppearanceTransition in these cases made the message go away, though is seems rather a patch for a symptom than a real remedy for the error.

score 0 · Answer 11 · answered Nov 17 '21 at 10:08

0

In React native I am getting this error while opening galley or camera screen. I set timeout before opening this screen and its works for me.

answered Nov 17 '21 at 10:08

Rajesh N

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score 0 · Answer 12 · answered Mar 22 '22 at 20:39

0

My UINavigationController was being presented, so had to replace UIModalPresentationCurrentContext with UIModalPresentationFullScreen on the presentation mechanism. Or you can use UIModalPresentationAutomatic if you have iOS 13.0 or more recent.

answered Mar 22 '22 at 20:39

Pedro Góes

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score -1 · Answer 13 · edited Nov 07 '21 at 04:57

-1

Are you using the appearance proxy feature?

I have found very problematic this feature, last time I have a

"Unbalanced calls to begin/end appearance transitions for"

I solved it removing the [[UITextField appearance] ..] methods.

edited Nov 07 '21 at 04:57

Nimantha

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answered Jun 25 '14 at 10:32

Eva Madrazo

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"Unbalanced calls to begin/end appearance transitions for DetailViewController" when pushing more than one detail view controller

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