How to debug CoreFoundation Crash run_animation_callbacks - objective-c

Question

I do not know how I can use the following crash report from crashlytics to narrow down the source of the crash.
All I understand is that it has something to do with CoreFoundation, but what exactly is the crash? And where in my code is it happening?
Is a CAAnimation Delegate? Or perhaps I did not remove and observer from NSNotifications?
Any ideas?
Crashed: com.apple.main-thread SIGABRT ABORT at 0x39a5cdf0
Thread : Crashed: com.apple.main-thread
0 libsystem_kernel.dylib 0x39a5cdf0 __pthread_kill + 8
1 libsystem_pthread.dylib 0x39addc97 pthread_kill + 62
2 libsystem_c.dylib 0x399fb939 abort + 76
3 libc++abi.dylib 0x38bfabbd __cxa_bad_cast
4 libc++abi.dylib 0x38c1466f default_terminate_handler() + 266
5 libobjc.A.dylib 0x393eef11 _objc_terminate() + 192
6 libc++abi.dylib 0x38c11def std::__terminate(void (*)()) + 78
7 libc++abi.dylib 0x38c115b1 __cxxabiv1::exception_cleanup_func(_Unwind_Reason_Code, _Unwind_Exception*)
8 libobjc.A.dylib 0x393eed4b objc_exception_throw + 250
9 CoreFoundation 0x2b4975fd __methodDescriptionForSelector
10 CoreFoundation 0x2b4954d9 ___forwarding___ + 712
11 CoreFoundation 0x2b3c49d8 _CF_forwarding_prep_0 + 24
12 QuartzCore 0x2e4eeff3 CA::Layer::run_animation_callbacks(void*) + 150
13 libdispatch.dylib 0x39958c6f _dispatch_client_callout + 22
14 libdispatch.dylib 0x39964553 _dispatch_main_queue_callback_4CF$VARIANT$mp + 1322
15 CoreFoundation 0x2b457889 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 8
16 CoreFoundation 0x2b455fa9 __CFRunLoopRun + 1512
17 CoreFoundation 0x2b3a19a1 CFRunLoopRunSpecific + 476
18 CoreFoundation 0x2b3a17b3 CFRunLoopRunInMode + 106
19 GraphicsServices 0x32b531a9 GSEventRunModal + 136
20 UIKit 0x2eb2c695 UIApplicationMain + 1440