时，该应用将崩溃
相同的代码运行到iPhone SE，或其他5s没有崩溃
崩溃的iPhone是iPhone5s。
此崩溃在 wkwebview
这是崩溃日志：
Code Type: ARM-64 (Native)
Parent Process: launchd [1]
Date/Time: 2017-02-21 19:28:26.069 +0800
Launch Time: 2017-02-21 19:27:45.145 +0800
OS Version: iOS 8.4.1 (12H321)
Report Version: 105
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread: 12
Last Exception Backtrace:
0 CoreFoundation 0x1846a022c __exceptionPreprocess + 132
1 libobjc.A.dylib 0x19631c0e4 objc_exception_throw + 60
2 CoreFoundation 0x1846a72f4 -[NSObject(NSObject) doesNotRecognizeSelector:] + 220
3 CoreFoundation 0x1846a40a8 ___forwarding___ + 928
4 CoreFoundation 0x1845a696c _CF_forwarding_prep_0 + 92
5 UIKit 0x189156814 -[UIGestureRecognizer _delegateShouldReceiveTouch:] + 152
6 UIKit 0x1891565f4 -[UITouchesEvent _addGestureRecognizersForView:toTouch:currentTouchMap:newTouchMap:] + 912
7 UIKit 0x18914977c -[UITouchesEvent _addTouch:forDelayedDelivery:] + 624
8 UIKit 0x1891494c0 _AddTouchToEvent + 196
9 UIKit 0x1893bdc80 _UIApplicationHandleEventFromQueueEvent + 14236
10 UIKit 0x18911b488 _UIApplicationHandleEventQueue + 1716
11 CoreFoundation 0x184657f8c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
ios8 set
allowsBackForwardNavigationGestures = YES;
然后设置
allowsBackForwardNavigationGestures = NO;
当您触摸wkwebview