iOS - nested push animation can result in corrupted navigation bar

Question

In my app, I have UIViewControllers A,B,C,D. What I do it traverse from A to B to C to D. Now the stack reads like A,B,C,D

I then remove C and D which are the top 2 items in the stack using

[self.navigationController popToViewController:BViewController animated:NO];

When I NSLog now I have A,B in the stack. Now when I try moving to C I get "nested push animation can result in corrupted navigation bar". I am puzzled why this is happening. Can anyone please help me in resolving this issue. Thanks for your time

EDIT From B I go to C using the below code

UIStoryboard *storybord = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
UIViewController *viewController = [storybord instantiateViewControllerWithIdentifier:@"C"];
[self.navigationController pushViewController:viewController animated:YES];

After this code is executed, there is an asynchronous code where we push to D

UIStoryboard *storybord = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
UIViewController *viewController = [storybord instantiateViewControllerWithIdentifier:@"D"];
[self.navigationController pushViewController:viewController animated:YES];

The stack now reads A,B,C,D. When I pop, the issue occurs

ASYNCHRONOUS CODE

 [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {

            if (error) {
                NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
                [defaults setValue:@"messagehomescreen" forKey:@"lastscreenstatus"];
                UIStoryboard *storybord = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
                UIViewController *viewController = [storybord instantiateViewControllerWithIdentifier:@"D"];
                [self.navigationController pushViewController:viewController animated:YES];

            } 
        }];

Answer 1

try

BViewController *BViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"BVC"];
[self.navigationController pushViewController: BViewController animated:YES];

Edit: Yes -pushviewcontroller will add controllers onto the stack. Please don't use it.

The -popToViewController is used to pop view controllers OFF the stack, down to one that already exists. But you have array of view controllers on the stack so you need to provide one of them as the argument like below code.

 [self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:1] animated:YES];

Please refer this link for further info.

Answer 2

I think your problem is that you are pushing asynchronously to the new ViewController.

You can't do any UI stuff in a background thread. It must all be in the main thread.

If you are running something in the background that may take a long time and then pushing to a new view controller then you must always go back to the main thread to push the view controller.