Recently our Crashlytics have been receiving a lot of crashes as title say. Strange thing is that it happen when users are on the WebView interface (base on logs). Here down below is my crash logs:
In crashed thread:
Crashed: WebThread
0 libdispatch.dylib 0x5e80 _dispatch_assert_queue_fail + 116
1 libdispatch.dylib 0x5e0c _dispatch_assert_queue_fail + 194
2 UIKitCore 0x200274 -[UIImageView _mainQ_beginLoadingIfApplicable] + 88
3 UIKitCore 0x1fe550 -[UIImageView setHidden:] + 76
4 UIKitCore 0xb714 -[UIButtonLegacyVisualProvider _updateBackgroundImageView] + 340
5 UIKitCore 0x4dab20 -[UIButtonLegacyVisualProvider layoutSubviews] + 168
6 UIKitCore 0x1bc718 -[UIButton layoutSubviews] + 68
7 UIKitCore 0x18c17c -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2592
8 QuartzCore 0x407fc CA::Layer::layout_if_needed(CA::Transaction*) + 532
9 QuartzCore 0x32c60 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 136
10 QuartzCore 0x475b4 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 452
11 QuartzCore 0x504a8 CA::Transaction::commit() + 704
12 QuartzCore 0x323a0 CA::Transaction::flush_as_runloop_observer(bool) + 88
13 CoreFoundation 0x410c4 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 36
14 CoreFoundation 0x10080 __CFRunLoopDoObservers + 592
15 CoreFoundation 0xb13c __CFRunLoopRun + 1052
16 CoreFoundation 0x1ebc8 CFRunLoopRunSpecific + 600
17 WebCore 0xbe9d9c <redacted> + 760
18 libsystem_pthread.dylib 0x19ac _pthread_start + 148
19 libsystem_pthread.dylib 0xe68 thread_start + 8Main thread Logs:
com.apple.main-thread
0 libsystem_kernel.dylib 0x1f24 __psynch_cvwait + 8
1 libsystem_pthread.dylib 0x8298 _pthread_cond_wait + 1236
2 JavaScriptCore 0x49d08 WTF::ParkingLot::parkConditionallyImpl(void const*, WTF::ScopedLambda<bool ()> const&, WTF::ScopedLambda<void ()> const&, WTF::TimeWithDynamicClockType const&) + 2076
3 JavaScriptCore 0x3a5e4 WTF::LockAlgorithm<unsigned char, (unsigned char)1, (unsigned char)2, WTF::EmptyLockHooks<unsigned char> >::lockSlow(WTF::Atomic<unsigned char>&) + 216
4 WebCore 0xbe7228 <redacted> + 280
5 WebCore 0xbe8418 WebThreadLock + 132
6 UIKitCore 0x1338354 -[UIWebView dealloc] + 32
7 RotimaticMobileProduction 0x19856c @objc RMWebViewController.__ivar_destroyer + 4333340012 (RMWebViewController.swift:4333340012)
8 libobjc.A.dylib 0x8380 object_cxxDestructFromClass(objc_object*, objc_class*) + 116
9 libobjc.A.dylib 0x51b4 objc_destructInstance + 80
10 libobjc.A.dylib 0xea00 _objc_rootDealloc + 80
11 UIKitCore 0x2fe220 -[UIResponder dealloc] + 156
12 UIKitCore 0x1c9074 -[UIViewController dealloc] + 1220
13 libobjc.A.dylib 0x7b14 AutoreleasePoolPage::releaseUntil(objc_object**) + 196
14 libobjc.A.dylib 0x3e54 objc_autoreleasePoolPop + 212
15 UIKitCore 0x1c9058 -[UIViewController dealloc] + 1192
16 UIKitCore 0x396794 -[UINavigationController dealloc] + 448
17 libobjc.A.dylib 0x7b14 AutoreleasePoolPage::releaseUntil(objc_object**) + 196
18 libobjc.A.dylib 0x3e54 objc_autoreleasePoolPop + 212
19 UIKitCore 0x328964 -[_UIAfterCACommitBlock run] + 92
20 UIKitCore 0x23bb4c -[_UIAfterCACommitQueue flush] + 192
21 UIKitCore 0x16523c _runAfterCACommitDeferredBlocks + 644
22 UIKitCore 0x165960 _cleanUpAfterCAFlushAndRunDeferredBlocks + 132
23 UIKitCore 0x53e6ec _UIApplicationFlushCATransaction + 84
24 UIKitCore 0x7d8d5c _UIUpdateSequenceRun + 84
25 UIKitCore 0xe5fedc schedulerStepScheduledMainSection + 144
26 UIKitCore 0xe5f6a4 runloopSourceCallback + 92
27 CoreFoundation 0xbb414 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28
28 CoreFoundation 0xcc1a0 __CFRunLoopDoSource0 + 208
29 CoreFoundation 0x5694 __CFRunLoopDoSources0 + 268
30 CoreFoundation 0xb05c __CFRunLoopRun + 828
31 CoreFoundation 0x1ebc8 CFRunLoopRunSpecific + 600
32 GraphicsServices 0x1374 GSEventRunModal + 164
33 UIKitCore 0x514b58 -[UIApplication _run] + 1100
34 UIKitCore 0x296090 UIApplicationMain + 364
35 RotimaticMobileProduction 0x36874 main + 28 (AppDelegate.swift:28)
36 ??? 0x103b21da4 (Missing)My question is what could possibly happen in this case? Our developer team have try to reproduce this crash on 15.6 and 16.0 ios device but nothing happen yet.