iOS 7.1 Crash: -[UINavigationBar setItems:animated:]

Question

I'm experiencing a crash that is brand new across all iPhone devices with iOS 7.1 and I'm wondering if others have seen the same.

Date/Time:           2014-03-11 11:46:00.795 -0700
OS Version:          iOS 7.1 (11D167)
Report Version:      104

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread:  6

Last Exception Backtrace:
0   CoreFoundation                       0x2d4dbefe __exceptionPreprocess + 126
1   libobjc.A.dylib                      0x37c70ce2 objc_exception_throw + 32
2   CoreFoundation                       0x2d4dbe40 +[NSException raise:format:] + 106
3   UIKit                                0x2fe319a0 -[UINavigationBar setItems:animated:] + 98
4   Document                             0x97aa6 -[FHHorizontalSplitViewController setVisibility:animated:] (FHHorizontalSplitViewController.m:233)
5   Document                             0x98882 __44-[FHHorizontalSplitViewReplaceSegue perform]_block_invoke (FHHorizontalSplitViewController.m:450)
6   Document                             0x9814a __72-[FHHorizontalSplitViewController _changeViewFramesAnimated:completion:]_block_invoke (FHHorizontalSplitViewController.m:335)
7   UIKit                                0x2fd43788 -[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 278
8   UIKit                                0x2fd433d2 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 172
9   UIKit                                0x2fd432ea -[UIViewAnimationState animationDidStop:finished:] + 60
10  QuartzCore                           0x2f98de06 CA::Layer::run_animation_callbacks(void*) + 228
11  libdispatch.dylib                    0x38159d3a _dispatch_client_callout + 16
12  libdispatch.dylib                    0x3815c6be _dispatch_main_queue_callback_4CF + 272
13  CoreFoundation                       0x2d4a6674 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 2
14  CoreFoundation                       0x2d4a4f40 __CFRunLoopRun + 1302
15  CoreFoundation                       0x2d40f7a4 CFRunLoopRunSpecific + 518
16  CoreFoundation                       0x2d40f586 CFRunLoopRunInMode + 100
17  GraphicsServices                     0x3237c6ce GSEventRunModal + 132
18  UIKit                                0x2fd6e88c UIApplicationMain + 1130
19  Document                             0x80dbe main (main.m:12)

The code in question (FHHorizontalSplitViewController) is a custom UIViewController container that is installed in a UINavigationController. The gist is it's splits the top and bottom halves of the iPhone screen and selections in the top half expands or contracts the bottom half. When a child-view controller has been expanded to fill the screen, the container asks it for its UINavigationItem and sets the navigation bar item.

The interesting thing is this crash is new on iOS 7.1; it works fine on 6.x and 7.0.x.

Have others seen new crashes in this method call that didn't happen before?

The crashing call site:

UINavigationController *navVC = self.navigationController;
if (navVC) {
    NSMutableArray *navigationItems = [NSMutableArray arrayWithArray:navVC.navigationBar.items;
    NSInteger lastItem = [navigationItems count] - 1;
    navigationItems[lastItem] = [self navigationItem];
    [navVC.navigationBar setItems:navigationItems animated:YES];
}

Answer 1

Calling -[UINavigationBar setItem:animated:] on a navigation bar that is being managed by a UINavigationController is disallowed (and newly enforced) in iOS 7.1