Question

So I have a UITabView Controller that was created in interface builder. The title and image properties of UITabBarItem were set in IB. A Tab Bar Controller object is present in the xib and all necessary connections are made. I am able to call simple commands such as

[tabBarController setSelectedIndex:1];

Everything works fine but when I set the ‘items’ property, I crash. Maybe I am having a memory management problem?

Here is the crashing code:

NSMutableArray *modifiedItems = [[tabBarController.tabBar items] mutableCopy];  
[modifiedItems removeObjectAtIndex:2];  
NSArray *newItems = [[NSArray alloc] initWithArray:modifiedItems];  
-->[tabBarController.tabBar setItems:newItems animated:NO];  

* Terminating app due to uncaught exception ‘NSInternalInconsistencyException’, reason: ‘Directly modifying a tab bar managed by a tab bar controller is not allowed.’
* Call stack at first throw:

0   CoreFoundation                      0x02b9bb99 __exceptionPreprocess + 185
1   libobjc.A.dylib                     0x02ceb40e objc_exception_throw + 47
2   CoreFoundation                      0x02b54238 +[NSException raise:format:arguments:] + 136
3   CoreFoundation                      0x02b541aa +[NSException raise:format:] + 58
4   UIKit                               0x005f7019 -[UITabBar setItems:animated:] + 2037
5   Zag Map                             0x00003422 -[ZagMapAppDelegate iPodTouchRemoval] + 270
6   Zag Map                             0x00002eea -[ZagMapAppDelegate applicationDidFinishLaunching:] + 551
7   UIKit                               0x003faf80 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1252
8   UIKit                               0x003fd3b0 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 346
9   UIKit                               0x004073ec -[UIApplication handleEvent:withNewEvent:] + 1958
10  UIKit                               0x003ffb3c -[UIApplication sendEvent:] + 71
11  UIKit                               0x004049bf _UIApplicationHandleEvent + 7672
12  GraphicsServices                    0x03357822 PurpleEventCallback + 1550
13  CoreFoundation                      0x02b7cff4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
14  CoreFoundation                      0x02add807 __CFRunLoopDoSource1 + 215
15  CoreFoundation                      0x02adaa93 __CFRunLoopRun + 979
16  CoreFoundation                      0x02ada350 CFRunLoopRunSpecific + 208
17  CoreFoundation                      0x02ada271 CFRunLoopRunInMode + 97
18  UIKit                               0x003fcc6d -[UIApplication _run] + 625
19  UIKit                               0x00408af2 UIApplicationMain + 1160
20  Zag Map                             0x00002ca0 main + 102
21  Zag Map                             0x00002c31 start + 53
    terminate called after throwing an instance of 'NSException'

My NSArray and NSMutableArray appear to be fine considering they came straight out of the functioning UITabBar. It returned three objects, then two. I hope I’m just overlooking something stupid here. Any ideas I would really appreciate.

Answer 1

The exception message tells you exactly what is wrong:

‘Directly modifying a tab bar managed by a tab bar controller is not allowed.’

Set the tab bar controller’s viewControllers property instead.