iOS Unknown Signal crash: Where to start? - ios

Question

I've received this crash report from TestFlight, but I've been unable to duplicate the crash in my own environment, and from the stack trace it doesn't seem to reference my own code at all. Any help in finding a jump off point for where to look would help, even if it's just advice on how to figure it out on my own.
Error: Unknown Signal
0 MyApp 0x000f3e96 testflight_backtrace + 142
1 MyApp 0x000f4a24 TFSignalHandler + 212
2 libsystem_c.dylib 0x36dbe7ec _sigtramp + 48
3 UIKit 0x32100f0e -[UIImageView(UIImageViewInternal) _canDrawContent] + 78
4 UIKit 0x320e530c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 940
5 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
6 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
7 UIKit 0x3210a8e2 -[UIScrollView _didMoveFromWindow:toWindow:] + 54
8 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
9 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
10 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
11 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
12 UIKit 0x320e5108 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 424
13 UIKit 0x320e4eec -[UIView(Hierarchy) _postMovedFromSuperview:] + 140
14 UIKit 0x320e59b4 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1168
15 UIKit 0x320e551e -[UIView(Hierarchy) addSubview:] + 30
16 UIKit 0x3217c1a4 -[UITransitionView transition:fromView:toView:] + 980
17 UIKit 0x3217bdc8 -[UITransitionView transition:toView:] + 104
18 UIKit 0x3217b994 -[UITabBarController transitionFromViewController:toViewController:transition:shouldSetSelected:] + 524
19 UIKit 0x3217b782 -[UITabBarController transitionFromViewController:toViewController:] + 30
20 UIKit 0x3217b0bc -[UITabBarController _setSelectedViewController:] + 300
21 UIKit 0x322045d8 -[UITabBarController _tabBarItemClicked:] + 344
22 CoreFoundation 0x3501e3fc -[NSObject performSelector:withObject:withObject:] + 52
23 UIKit 0x320fdfae -[UIApplication sendAction:to:from:forEvent:] + 62
24 UIKit 0x320fdf6a -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 30
25 UIKit 0x3220445c -[UITabBar _sendAction:withEvent:] + 352
26 CoreFoundation 0x3501e3fc -[NSObject performSelector:withObject:withObject:] + 52
27 UIKit 0x320fdfae -[UIApplication sendAction:to:from:forEvent:] + 62
28 UIKit 0x320fdf6a -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 30
29 UIKit 0x320fdf48 -[UIControl sendAction:to:forEvent:] + 44
30 UIKit 0x320fdcb8 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 492
31 UIKit 0x322041ec -[UITabBar(Static) _buttonUp:] + 116
32 CoreFoundation 0x3501e3fc -[NSObject performSelector:withObject:withObject:] + 52
33 UIKit 0x320fdfae -[UIApplication sendAction:to:from:forEvent:] + 62
34 UIKit 0x320fdf6a -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 30
35 UIKit 0x320fdf48 -[UIControl sendAction:to:forEvent:] + 44
36 UIKit 0x320fdcb8 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 492
37 UIKit 0x320fe5f0 -[UIControl touchesEnded:withEvent:] + 476
38 UIKit 0x320fcad2 -[UIWindow _sendTouchesForEvent:] + 318
39 UIKit 0x320fc4c0 -[UIWindow sendEvent:] + 380
40 UIKit 0x320e283c -[UIApplication sendEvent:] + 356
41 UIKit 0x320e20e2 _UIApplicationHandleEvent + 5826
42 GraphicsServices 0x3631722a PurpleEventCallback + 882
43 CoreFoundation 0x35098522 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 38
44 CoreFoundation 0x350984c4 __CFRunLoopDoSource1 + 140
45 CoreFoundation 0x35097312 __CFRunLoopRun + 1370
46 CoreFoundation 0x3501a4a4 CFRunLoopRunSpecific + 300
47 CoreFoundation 0x3501a36c CFRunLoopRunInMode + 104
48 GraphicsServices 0x36316438 GSEventRunModal + 136
49 UIKit 0x32110e7c UIApplicationMain + 1080
50 WiseLaw 0x0009365e main (main.m:14)
51 WiseLaw 0x00093617 start + 39

Answer 1

As a vague hint, it might be caused when selecting a tab in UITabViewController and subsequently drawing a UIImageView. Maybe you are referencing a zombie object somewhere.
The stack trace you have doesn't help a lot, try to get the original iOS crash report from the device. The crash could also have been triggered on another thread.
You might want to try a crash reporting solution based on the PLCrashReporter framework, which will show you all threads and also shows the Last Exception Backtrace, if the crash is actually caused by an exception and re-thrown into another runloop. The project page shows some open source and hosted solutions that are based on it: http://code.google.com/p/plcrashreporter/

Answer 2

These link might help in resolving the crash
http://www.raywenderlich.com/10209/my-app-crashed-now-what-part-1
http://www.raywenderlich.com/10505/my-app-crashed-now-what-part-2
Try to use DDLog instead of nslog ,It helps in tracking bugs
Link for DDLog sample code:=
https://github.com/robbiehanson/CocoaLumberjack