Pushing the same view controller instance more than once is not supported

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Level 1

19 points

Pushing the same view controller instance more than once is not supported

I get this exception if I push a UIViewController which has the same class as one which has already been pushed on a UINavigationViewController stack. Is this a new restriction?

Is there a way around this other than inspecting the contents of UINavigationViewController.viewControllers before pushing?

MacBook, Mac OS X (10.5.6)

Posted on Dec 16, 2008 6:01 PM

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Answer 1

Dave iMac Author

Level 1

19 points

Dec 16, 2008 6:04 PM in response to Dave iMac

...BTW the message in the exception is surely wrong since it talks about an instance not a class but the code is preventing different instances of the same class being pushed.

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Answer 2

rab101

Level 1

6 points

Dec 28, 2008 8:27 PM in response to Dave iMac

The doc says that nothing will happen if it is already pushed on the stack. It will not bring it up. I used this in the past and it was behaving like it says in the docs. It was not crashing. I did not try it in the latest SDK.

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Answer 3

Jan 3, 2009 2:06 PM in response to Dave iMac

Hi,

I'm seeing the same issue. The app ran fine in the simulator. I then switched to 'release' mode, and tried to compile and run on a device (iPod Touch). Now I see this error. What gives?

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Answer 4

Jan 3, 2009 2:10 PM in response to slashzero

I should also point out I'm using the latest iPhone SDK, compiling for OS 2.2. I get the same error in Debug or Release (if it matters).

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Answer 5

Jan 3, 2009 2:26 PM in response to slashzero

OK. Fixed this issue in my code. I had pushViewController twice in one method. This causes the application to crash!

For example:

+[self.navigationController pushViewController:self.aView animated:YES];+
+// some code+
+// ...+
+[self.navigationController pushViewController:self.aView animated:YES];+

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Answer 6

dev007

Level 1

0 points

Jan 8, 2009 1:33 AM in response to Dave iMac

Hi Dave,

and how did you inspect the contents of UINavigationViewCOntroller.viewControllers?

I also get this exception. I have three ViewControllers, which get pushed on the navigation controller's stack. When I pop the third controller, I get this exception.

Funny thing is, I do NOT push the next view controller (cause it is already on the stack), i POP the last one, which normally (in iPhone OS 2.1) has the result, that the view controller, which was shown before the one I pop, will get shown again.

But in iPhone OS 2.2, when I pop that last view controller, there occurs this strange exception.

Anyone any ideas? 🙂

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Answer 7

Jan 21, 2009 2:07 PM in response to dev007

Hi,

I have the same problem. Have you found the solution?

Thanks

Alexandre

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Answer 8

dev007

Level 1

0 points

Mar 2, 2009 7:10 AM in response to Kryten002

I did not continue to develop since your post, so I did not find any solutions about that problem, sorry!

Does anyone else have a clue, where this exception comes from? 🙂

Greetz,
dev007

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Answer 9

dev007

Level 1

0 points

Mar 2, 2009 7:33 AM in response to Kryten002

Even better....

popToRootController() works, but popViewController() throws the exception... 🙂

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Answer 10

rkam

Level 1

0 points

Mar 10, 2009 4:17 PM in response to dev007

I had the same issue when I had both text field's - Editing did end event and buttons - touch up inside event calling the same method.. which caused it push it twice.

So I remove the text fields event method.. with which it went away.

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