UINavigationController popViewControllerAnimated: crash in iOS 6

Question

The code below works fine in iOS 4 and 5 but crashes in iOS 6 with EXC_BAD_ACCESS. I'd appreciate any help in troubleshooting it. This code is being called in a UITableViewController that handles my app's search logic:

CATransition *transition = [CATransition animation];
transition.duration = 0.3f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
transition.type = kCATransitionFade;

[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController popViewControllerAnimated:NO];

The way I add the tableView is similar and doesn't crash when called:

SearchTVC *searchTable = [[SearchTVC alloc] init];
searchTable.detailViewController = self.detailViewController;

CATransition *transition = [CATransition animation];
transition.duration = 0.3f;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
transition.type = kCATransitionFade;

[self.navigationController.view.layer addAnimation:transition forKey:nil];
[self.navigationController pushViewController:searchTable animated:NO];

What could be the problem?

*EDIT

Interestingly the crash doesn't occur if I use [self.navigationController popViewControllerAnimated:YES]; (YES rather than NO). But of course this defeats the purpose of using a custom pop animation.

More details about the crash would help; I'm reminded of http://stackoverflow.com/questions/11584607/how-to-prevent-crash-on-cancel-of-mfmailcomposeviewcontroller/11588677#11588677 — tc., Sep 24 '12 at 23:34

score 7 · Answer 1 · answered Aug 06 '13 at 21:44

7

Check whether you have a line like the following somewhere in your view controller code:

self.navigationController.delegate=self;

If so, then you must set it back

self.navigationController.delegate=nil;

before you say

[self.navigationController popViewControllerAnimated:YES];

Otherwise, popViewControllerAnimated will first deallocate the delegate and then try to call it - resulting in a crash.

answered Aug 06 '13 at 21:44

LPG

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resetting the navigation controller's delegate appears to need to happen in `viewWillDisappear:`. Doing it in `viewDidDisappear:` seems to work sometimes, but not all the time, and `viewWillDisappear:` still allows the delegate to control any custom transitions. – Ian Jan 08 '14 at 19:05
Many thanks. It would have taken me a long time to find this. It's a very obnoxious time-bomb based crash deep in iOS internal stack. – BaseZen Feb 15 '16 at 23:47

score 3 · Accepted Answer · edited May 23 '17 at 10:27

3

I know my question was vague, but I didn't have much else to go off of. I knew the line [self.navigationController popViewControllerAnimated:NO]; was the problem but I couldn't figure out why. Then I came across this question and the first answer suggested I make my search table an instance variable rather than creating a new one every time I want to present it, and that actually worked. It must be a memory issue that I can't wrap my head around.

tl;dr :

Make sure the UIViewController that's being pushed and popped is an instance variable.

edited May 23 '17 at 10:27

Community

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answered Sep 25 '12 at 13:16

lobianco

6,226
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1

Love the TLDR version. It made the most sense to me, and more importantly... worked. – Evan K. Stone Aug 06 '15 at 17:13

score 1 · Answer 3 · answered May 11 '18 at 20:06

1

Though super late to party... Hope this might help someone in future. I opened a very old code...

Enabling ARC mode and then resolving all the compiler warnings/error fixed it automatically.

answered May 11 '18 at 20:06

jeet.chanchawat

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UINavigationController popViewControllerAnimated: crash in iOS 6

3 Answers3

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