Unrecognized selector sent to instance (self.navigationController.toolbar) - iphone

Question

I've been banging my head against the wall for the past 2 days with it - and I need help.
In my controller, I have this code:
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationController.toolbar.barStyle = UIBarStyleBlack;
[self.navigationController setToolbarHidden:NO];
... // the rest of initialisation goes here
}
This controller presents details of one item selected from the list. Controller displaying a list of items does pushViewControllerAnimated on this controller to display details of the item selected by the user.
This works fine on the first execution, however when the user presses back button - and then selects another (or even the same) item from the list, line [self.navigationController setToolbarHidden:NO] causes SIGABRT with this stack trace:
2011-11-04 10:24:21.423 OOKL[32026:10403] -[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0
2011-11-04 10:24:21.426 OOKL[32026:10403] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0'
*** Call stack at first throw:
(
0 CoreFoundation 0x019875a9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x01adb313 objc_exception_throw + 44
2 CoreFoundation 0x019890bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x018f8966 ___forwarding___ + 966
4 CoreFoundation 0x018f8522 _CF_forwarding_prep_0 + 50
5 UIKit 0x0063223e -[UIToolbar setItems:animated:] + 1554
6 UIKit 0x005f8ccb -[UIViewController(UINavigationControllerContextualToolbar) setToolbarItems:] + 49
7 OOKL 0x0003df87 -[OOExplorerObjectDetailController setUpToolbarForExplore] + 1335
8 OOKL 0x0003eb2b -[OOExplorerObjectDetailController viewDidLoad] + 2043
9 UIKit 0x005fd089 -[UIViewController view] + 179
10 UIKit 0x005fb482 -[UIViewController contentScrollView] + 42
11 UIKit 0x0060bf25 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48
12 UIKit 0x0060a555 -[UINavigationController _layoutViewController:] + 43
13 UIKit 0x0060b870 -[UINavigationController _startTransition:fromViewController:toViewController:] + 524
14 UIKit 0x0060632a -[UINavigationController _startDeferredTransitionIfNeeded] + 266
15 UIKit 0x0060d562 -[UINavigationController pushViewController:transition:forceImmediate:] + 932
16 UIKit 0x006061c4 -[UINavigationController pushViewController:animated:] + 62
17 OOKL 0x0002ed8b -[OOExploreController showObjectDetailControllerWithObject:] + 571
18 OOKL 0x0002da1c -[OOExploreController parserDidFinish:] + 316
19 OOKL 0x00021c13 -[OOXMLParser parserDidEndDocument:] + 99
20 Foundation 0x00385717 _endDocument + 95
21 libxml2.2.dylib 0x02ad4215 xmlParseChunk + 7380
22 Foundation 0x0038615a -[NSXMLParser parse] + 321
23 OOKL 0x00021893 -[OOXMLParser parseString:] + 339
24 OOKL 0x0002d8d5 -[OOExploreController parseXml:] + 165
25 OOKL 0x0002d81f -[OOExploreController requestDidFinishLoading:] + 79
26 OOKL 0x00011cba -[OOSharedSeverController connectionDidFinishLoading:] + 298
27 Foundation 0x002ef112 -[NSURLConnection(NSURLConnectionReallyInternal) sendDidFinishLoading] + 108
28 Foundation 0x002ef06b _NSURLConnectionDidFinishLoading + 133
29 CFNetwork 0x013cd48e _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 220
30 CFNetwork 0x014986e1 _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 293
31 CFNetwork 0x013c3c80 _ZN19URLConnectionClient13processEventsEv + 100
32 CFNetwork 0x013c3acf _ZN17MultiplexerSource7performEv + 251
33 CoreFoundation 0x019688ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
34 CoreFoundation 0x018c688b __CFRunLoopDoSources0 + 571
35 CoreFoundation 0x018c5d86 __CFRunLoopRun + 470
36 CoreFoundation 0x018c5840 CFRunLoopRunSpecific + 208
37 CoreFoundation 0x018c5761 CFRunLoopRunInMode + 97
38 GraphicsServices 0x01e601c4 GSEventRunModal + 217
39 GraphicsServices 0x01e60289 GSEventRun + 115
40 UIKit 0x0055bc93 UIApplicationMain + 1160
41 OOKL 0x00002d09 main + 121
42 OOKL 0x00002c85 start + 53
)
I thought, maybe, I should setup self.toolbarItems first before making the toolbar visible - but then I get this same error when I do
self.toolbarItems = [NSArray ...]
I'm desperate now - any help is appreciated.
Edit: Now for some reason I'm getting EXC_BAD_ACCESS instead of SIGABRT - in the same place - and no stack trace is produced at all.

Answer 1

As the stack trace tells:
-[NSCFNumber view]: unrecognized selector sent to instance 0x69db0e0
You are accidentally overreleasing something that is leading to this message sent to some dangling pointer (reference to some junk).
Check if you are releasing your navigationController, ViewController or anything where your workflow begins.