我们在基金会遇到了崩溃，但我们无法发现可能出现的问题。我们认为动画可能会引发这个问题。
有人遇到过这种崩溃吗？这是问题的痕迹。
Crashed: com.apple.main-thread
0 libobjc.A.dylib 0x1dfc44e6 objc_msgSend + 5
1 Foundation 0x1f7b0e77 -[_NSConcreteObservation dealloc] + 96
2 libobjc.A.dylib 0x1dfd1195 objc_object::sidetable_release(bool) + 238
3 Foundation 0x1f679e9d empty + 32
4 Foundation 0x1f5d4787 -[NSConcreteMapTable removeAllItems] + 76
5 UIKit 0x246e5259 -[UIView(AdditionalLayoutSupport) _clearLayoutVariableObservationsOnlyToSupportTAMICChange:] + 56
6 UIKit 0x23efaa0b __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 380
7 Foundation 0x1f5f7b03 -[NSISEngine withBehaviors:performModifications:] + 262
8 UIKit 0x23df6e8b -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 220
9 UIKit 0x23efab91 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke_2 + 170
10 UIKit 0x23efaaa7 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 536
11 Foundation 0x1f5f7b03 -[NSISEngine withBehaviors:performModifications:] + 262
12 UIKit 0x23df6e8b -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 220
13 UIKit 0x23efab91 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke_2 + 170
14 UIKit 0x23efaaa7 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 536
15 Foundation 0x1f5f7b03 -[NSISEngine withBehaviors:performModifications:] + 262
16 UIKit 0x23df6e8b -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 220
17 UIKit 0x23df6737 __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke + 92
18 Foundation 0x1f5f7b03 -[NSISEngine withBehaviors:performModifications:] + 262
19 UIKit 0x23df6607 -[UIView(Hierarchy) _postMovedFromSuperview:] + 754
20 UIKit 0x240e8949 __UIViewWasRemovedFromSuperview + 154
21 UIKit 0x23df57a5 -[UIView(Hierarchy) removeFromSuperview] + 1188
22 UIKit 0x24768167 __46-[UIInputWindowController invalidateInputView]_block_invoke + 120
23 UIKit 0x241872b9 -[UIResponder _preserveResponderOverridesWhilePerforming:] + 108
24 UIKit 0x247680eb -[UIInputWindowController invalidateInputView] + 108
25 UIKit 0x24768a17 -[UIInputWindowController changeToInputViewSet:] + 240
26 UIKit 0x24769d91 __43-[UIInputWindowController setInputViewSet:]_block_invoke.1331 + 26
27 UIKit 0x2476382d __77-[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:]_block_invoke.932 + 404
28 UIKit 0x23e3363b -[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 440
29 UIKit 0x23e33109 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 214
30 UIKit 0x23e32f91 -[UIViewAnimationState animationDidStop:finished:] + 128
31 QuartzCore 0x21c06ee7 CA::Layer::run_animation_callbacks(void*) + 252
32 libdispatch.dylib 0x1e3fa083 _dispatch_client_callout + 22
33 libdispatch.dylib 0x1e3fe5fd _dispatch_main_queue_callback_4CF + 890
34 CoreFoundation 0x1ed104a7 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 8
35 CoreFoundation 0x1ed0e78f __CFRunLoopRun + 1422
36 CoreFoundation 0x1ec5d533 CFRunLoopRunSpecific + 486
37 CoreFoundation 0x1ec5d341 CFRunLoopRunInMode + 104
38 GraphicsServices 0x20434bfd GSEventRunModal + 156
39 UIKit 0x23e65e67 -[UIApplication _run] + 574
40 UIKit 0x23e60591 UIApplicationMain + 150
41 App 0xb3c158 main (AppDelegate.swift:22)
42 libdispatch.dylib 0x1e42750b (Missing)