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.

Answer 1

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.

Answer 2

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.