UINavigationController not popping UINavigationBar items

Question

I'm having a problem where my UINavigationBar isn't popping it's items when the UINavigationController pops a view controller.

I have had a look at the stacks observed the following:

• The expected number of navigation controllers allocated (checked in instruments)
• There are the correct number of controllers on the stack. (debug logging)
• The navigation items aren't being popped. (debug logging)

Here's what I did.

I popped some log statements into the viewDidLoad method after calling super.

NSLog(@"%@", [self navigationController]);
NSLog(@"%@", [[self navigationController] viewControllers]);
NSLog(@"%@", [[self navigationController] navigationBar]);
NSLog(@"%@", [[[self navigationController] navigationBar] items]);

After the initial view is loaded.

2009-10-09 16:42:51.706 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:42:51.720 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>
)
2009-10-09 16:42:51.742 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:42:51.758 Bob[11657:207] (
    <UINavigationItem: 0x242d60>
)

All looks good. Push the second controller.

2009-10-09 16:43:11.800 Bob[11657:207] -[MediaBrowser beginLoading] [Line 261] 
2009-10-09 16:43:12.320 Bob[11657:207] -[MediaBrowser loadingComplete] [Line 269] 
2009-10-09 16:43:12.587 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:43:12.654 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>,
    <MediaBrowser: 0x2c1cc0>
)
2009-10-09 16:43:12.685 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:43:12.734 Bob[11657:207] (
    <UINavigationItem: 0x242d60>,
    <UINavigationItem: 0x2c63b0>
)

Again nothing unexpected here. Push the third controller.

2009-10-09 16:43:19.934 Bob[11657:207] -[MediaBrowser beginLoading] [Line 261] 
2009-10-09 16:43:20.388 Bob[11657:207] -[MediaBrowser loadingComplete] [Line 269] 
2009-10-09 16:43:20.928 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:43:20.962 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>,
    <MediaBrowser: 0x2c1cc0>,
    <MediaBrowser: 0x4027e20>
)
2009-10-09 16:43:21.003 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:43:21.039 Bob[11657:207] (
    <UINavigationItem: 0x242d60>,
    <UINavigationItem: 0x2c63b0>,
    <UINavigationItem: 0x4028880>
)

All good. Now lets pop a controller

2009-10-09 16:43:26.935 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:43:26.945 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>,
    <MediaBrowser: 0x2c1cc0>
)
2009-10-09 16:43:26.964 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:43:26.977 Bob[11657:207] (
    <UINavigationItem: 0x242d60>,
    <UINavigationItem: 0x2c63b0>,
    <UINavigationItem: 0x4028880>
)

Humm. Something is going amiss. The controller has popped but the navigation item is still there. For giggles lets push again.

009-10-09 16:44:05.878 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:44:05.908 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>,
    <MediaBrowser: 0x2c1cc0>,
    <MediaBrowser: 0x407eb00>
)
2009-10-09 16:44:05.951 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:44:05.996 Bob[11657:207] (
    <UINavigationItem: 0x242d60>,
    <UINavigationItem: 0x2c63b0>,
    <UINavigationItem: 0x4028880>,
    <UINavigationItem: 0x407f280>
)

The controller stack looks good, the navigation item stack is in lots of trouble. Lets pop one last time.

2009-10-09 16:44:17.770 Bob[11657:207] <UINavigationController: 0x243bb0>
2009-10-09 16:44:17.776 Bob[11657:207] (
    <MediaBrowser: 0x2354c0>,
    <MediaBrowser: 0x2c1cc0>
)
2009-10-09 16:44:17.785 Bob[11657:207] <UINavigationBar: 0x243e50; frame = (0 20; 320 44); autoresize = W; layer = <CALayer: 0x243ed0>>
2009-10-09 16:44:17.793 Bob[11657:207] (
    <UINavigationItem: 0x242d60>,
    <UINavigationItem: 0x2c63b0>,
    <UINavigationItem: 0x4028880>,
    <UINavigationItem: 0x407f280>
)

So the controller stack is fine. Navigation items on the other hand have some issues.

I'm stumped. I'm sure I'm doing something odd/weird/wrong but damn me if I can see it.The only manipulation i'm going is preparing (via my controllers navigationItem property) a custom rightBarItem.

If you got this far, thanks. Thoughts on where I might go from here would be appreciated.

Answer 1

Nailed it.

So it turns out that I was doing something stupid.

I had added a pop method in an internal category to NSMutableArray. That method wasn't popping correctly. UINavigationBar must also add a pop method to NSMutableArray. My buggy one was winning and breaking the pop of the UIBarItem.