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Editorial Team
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Asked: 2026-05-25T02:35:47+00:00

I’m a bit confused about the following code. If I comment out the second

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I’m a bit confused about the following code. If I comment out the second statement, it successfully shows the view: 

MyAppDelegate *delegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];

delegate.navController.viewControllers = [NSArray arrayWithObject:aViewController];

[delegate.navController pushViewController:aViewController animated:YES];

[aViewController release];

Otherwise, it crashes on the following: 

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Pushing the same view controller instance more than once is not supported

I add a different view controller in the app delegate, but not this one. What could be making it think it’s the same one?

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1 Answer

  1. Editorial Team
    delegate.navController.viewControllers = [NSArray arrayWithObject:aViewController];

[delegate.navController pushViewController:aViewController animated:YES];

    First line set’s aViewController as navController’s only controller. Second line pushes aViewController to navController again so yeah, no wonder you get it twice. Depending on what you want to do, ditch one of those two lines.

    If you want to set aViewController as only controller on navController, keep first line.

    If you want to push aViewController as a new controller on navController, keep second line.

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