我有一个崩溃的 UIBarButtonItem，但我不知道发生了什么。它不会在调试器上产生任何错误，它的崩溃日志也没有象征某些部分。这是崩溃日志：
Last Exception Backtrace:
0 CoreFoundation 0x354ba88f __exceptionPreprocess + 163
1 libobjc.A.dylib 0x37861259 objc_exception_throw + 33
2 CoreFoundation 0x354ba789 +[NSException raise:format:] + 1
3 Foundation 0x34fa23ff -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 87
4 Exame_iPhone 0x000b9029 0x4b000 + 450601
5 Exame_iPhone 0x000b9071 0x4b000 + 450673
6 Exame_iPhone 0x0010a60d 0x4b000 + 783885
7 Exame_iPhone 0x0010aa7b 0x4b000 + 785019
8 Exame_iPhone 0x00069ff3 0x4b000 + 126963
9 CoreFoundation 0x354143fd -[NSObject performSelector:withObject:withObject:] + 53
10 UIKit 0x32f09e07 -[UIApplication sendAction:to:from:forEvent:] + 63
11 UIKit 0x32fcf5e7 -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 119
12 CoreFoundation 0x354143fd -[NSObject performSelector:withObject:withObject:] + 53
13 UIKit 0x32f09e07 -[UIApplication sendAction:to:from:forEvent:] + 63
14 UIKit 0x32f09dc3 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 31
15 UIKit 0x32f09da1 -[UIControl sendAction:to:forEvent:] + 45
16 UIKit 0x32f09b11 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 493
17 UIKit 0x32f0a449 -[UIControl touchesEnded:withEvent:] + 477
18 UIKit 0x32f0892b -[UIWindow _sendTouchesForEvent:] + 319
19 UIKit 0x32f08319 -[UIWindow sendEvent:] + 381
20 UIKit 0x32eee695 -[UIApplication sendEvent:] + 357
21 UIKit 0x32eedf3b _UIApplicationHandleEvent + 5827
22 GraphicsServices 0x370ad22b PurpleEventCallback + 883
23 CoreFoundation 0x3548e523 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 39
24 CoreFoundation 0x3548e4c5 __CFRunLoopDoSource1 + 141
25 CoreFoundation 0x3548d313 __CFRunLoopRun + 1371
26 CoreFoundation 0x354104a5 CFRunLoopRunSpecific + 301
27 CoreFoundation 0x3541036d CFRunLoopRunInMode + 105
28 GraphicsServices 0x370ac439 GSEventRunModal + 137
29 UIKit 0x32f1ccd5 UIApplicationMain + 1081
30 Exame_iPhone 0x0004c23b 0x4b000 + 4667
31 Exame_iPhone 0x0004c1e0 0x4b000 + 4576
Thread 0 name: Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0 libsystem_kernel.dylib 0x35d7032c __pthread_kill + 8
1 libsystem_c.dylib 0x328bc208 pthread_kill + 48
2 libsystem_c.dylib 0x328b5298 abort + 88
3 libc++abi.dylib 0x35872f64 abort_message + 40
4 libc++abi.dylib 0x35870346 _ZL17default_terminatev + 18
5 libobjc.A.dylib 0x37861350 _objc_terminate + 140
6 libc++abi.dylib 0x358703be _ZL19safe_handler_callerPFvvE + 70
7 libc++abi.dylib 0x3587044a std::terminate() + 14
8 libc++abi.dylib 0x3587181e __cxa_rethrow + 82
9 libobjc.A.dylib 0x378612a2 objc_exception_rethrow + 6
10 CoreFoundation 0x35410506 CFRunLoopRunSpecific + 398
11 CoreFoundation 0x35410366 CFRunLoopRunInMode + 98
12 GraphicsServices 0x370ac432 GSEventRunModal + 130
13 UIKit 0x32f1ccce UIApplicationMain + 1074
14 Exame_iPhone 0x0004c234 0x4b000 + 4660
15 Exame_iPhone 0x0004c1d8 0x4b000 + 4568
有人知道发生了什么吗？
问候！