Need help in finding crash cause

Question

Below are the crash logs from an iPad. I'm getting this crash randomly while I'm pushing and popping out a UIViewController from Navigation controller. Any help/pointer is appreciated.

    Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
        Exception Codes: KERN_INVALID_ADDRESS at 0x00000000
        Crashed Thread:  0

        Thread 0 name:  Dispatch queue: com.apple.main-thread
        Thread 0 Crashed:

   0   libobjc.A.dylib                  0x31430386 _ZL12realizeClassP7class_t + 34
    1   libobjc.A.dylib                 0x314303e6 _ZL12realizeClassP7class_t + 130
    2   libobjc.A.dylib                 0x3142a836 prepareForMethodLookup + 74
    3   libobjc.A.dylib                 0x3142a740 lookUpMethod + 40
    4   libobjc.A.dylib                 0x3142a70c _class_lookupMethodAndLoadCache3 + 12
    5   libobjc.A.dylib                 0x31429fc4 objc_msgSend_uncached + 20
    6   UIKit                           0x3186553e -[UINavigationItem _accumulateViewsFromItems:isLeft:refreshViews:] + 270
    7   UIKit                           0x31851244 -[UINavigationItem _updateViewsForBarSizeChangeAndApply:] + 124
    8   UIKit                           0x319e023a __33-[UINavigationBar layoutSubviews]_block_invoke_0 + 250
    9   UIKit                           0x31838b46 +[UIView(Animation) _performWithoutAnimation:] + 62
    10  UIKit                           0x3184d2e2 -[UINavigationBar layoutSubviews] + 382
    11  UIKit                           0x31814f30 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 176
    12  CoreFoundation                  0x315431f4 -[NSObject performSelector:withObject:] + 36
    13  QuartzCore                      0x35459a9e -[CALayer layoutSublayers] + 210
    14  QuartzCore                      0x354596b6 CA::Layer::layout_if_needed(CA::Transaction*) + 210
    15  QuartzCore                      0x3545d83c CA::Context::commit_transaction(CA::Transaction*) + 220
    16  QuartzCore                      0x3545d578 CA::Transaction::commit() + 308
    17  QuartzCore                      0x354554b2 CA:::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 50
    18  CoreFoundation                  0x315b8b14 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 12
    19  CoreFoundation                  0x315b6d50 __CFRunLoopDoObservers + 252
    20  CoreFoundation                  0x315b70aa __CFRunLoopRun + 754
    21  CoreFoundation                  0x3153a49e CFRunLoopRunSpecific + 294
    22  CoreFoundation                  0x3153a366 CFRunLoopRunInMode + 98
    23  GraphicsServices                0x32a13432 GSEventRunModal + 130
    24  UIKit                           0x3183fcce UIApplicationMain + 1074
    25  SmartClassTPS                   0x000b551a main (main.m:16)
    26  SmartClassTPS                   0x000b5170 start + 32

Answer 1

Was able to figure out long back but forgot to update here. KVO observer not removed! Silly me :-|. BTW thanks for the support. SO rocks.

Answer 2

最有可能您忘记了在释放对象之前清除一些委托。