无法从堆栈跟踪中找出崩溃发生的代码片段，但是从面包屑中发现它发生在各个地方。不只是一个。可能是什么原因呢？
Crashed Thread
0 CoreFoundation 0x30c1aecb __exceptionPreprocess + 131
1 libobjc.A.dylib 0x3b3b5ce7 objc_exception_throw + 36
2 CoreFoundation 0x30c1ae0d +[NSException raise:format:] + 110
3 UIKit 0x33457ae5 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 106
4 UIKit 0x33457a73 -[UIView(Hierarchy) addSubview:] + 28
5 UIKit 0x336208bd __53-[_UINavigationParallaxTransition animateTransition:]_block_invoke + 1194
6 UIKit 0x3345e0b5 +[UIView(Animation) performWithoutAnimation:] + 70
7 UIKit 0x336201cd -[_UINavigationParallaxTransition animateTransition:] + 730
8 UIKit 0x335dd3b1 -[UINavigationController _startCustomTransition:] + 2614
9 UIKit 0x334fa46f -[UINavigationController _startDeferredTransitionIfNeeded:] + 416
10 UIKit 0x334fa279 -[UINavigationController __viewWillLayoutSubviews] + 42
11 UIKit 0x334fa211 -[UILayoutContainerView layoutSubviews] + 182
12 UIKit 0x3344c2e5 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 378
13 QuartzCore 0x330c831b -[CALayer layoutSublayers] + 140
14 QuartzCore 0x330c3b3f _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 348
15 QuartzCore 0x330c39d1 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 14
16 QuartzCore 0x330c33e5 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 226
17 QuartzCore 0x330c31f7 _ZN2CA11Transaction6commitEv + 312
18 UIKit 0x3344f99f _UIApplicationHandleEventQueue + 8268
19 CoreFoundation 0x30be5faf __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 12
20 CoreFoundation 0x30be5477 __CFRunLoopDoSources0 + 204
21 CoreFoundation 0x30be3c67 __CFRunLoopRun + 628
22 CoreFoundation 0x30b4e729 CFRunLoopRunSpecific + 522
23 CoreFoundation 0x30b4e50b CFRunLoopRunInMode + 104
24 GraphicsServices 0x35abd6d3 GSEventRunModal + 136
25 UIKit 0x334af871 UIApplicationMain + 1134
26 feelgood 0x00341d47 main (main.m:16)
27 libdyld.dylib 0x3b8b3ab7 start + 0