我有这个堆栈跟踪：
0 LiveTexOpClient 0x000b3d3a testflight_backtrace + 382
1 LiveTexOpClient 0x000b4988 TFSignalHandler + 264
2 libsystem_c.dylib 0x3c4d0e92 _sigtramp + 42
3 CoreFoundation 0x342edb4f CFBasicHashFindBucket + 1891
4 CoreFoundation 0x342edb4f CFBasicHashFindBucket + 1891
5 CoreFoundation 0x342eea8a CFDictionaryGetValue + 82
6 CoreFoundation 0x343357a6 -[CFXPreferencesPropertyListSource setValue:forKey:] + 38
7 CoreFoundation 0x34335722 _CFXPreferencesSetValue + 134
8 CoreFoundation 0x34335600 CFPreferencesSetAppValue + 40
9 Foundation 0x34c1c906 -[NSUserDefaults(NSUserDefaults) setObject:forKey:] + 82
10 LiveTexOpClient 0x0006db28 -[LTAuthorizationManager saveLatestSessionTimeStamp] (LTAuthorizationManager.m:390)
11 LiveTexOpClient 0x0002d7aa -[LTAppDelegate applicationWillResignActive:] (LTAppDelegate.m:48)
12 UIKit 0x36209fb4 -[UIApplication _deactivateForReason:notify:] + 400
13 UIKit 0x3623ff2a -[UIApplication _handleApplicationSuspend:eventInfo:] + 314
14 UIKit 0x361b61e6 -[UIApplication handleEvent:withNewEvent:] + 2458
15 UIKit 0x361b56cc -[UIApplication sendEvent:] + 72
16 UIKit 0x361b511a _UIApplicationHandleEvent + 6154
17 GraphicsServices 0x37eb85a2 _PurpleEventCallback + 590
18 GraphicsServices 0x37eb81d2 PurpleEventCallback + 34
19 CoreFoundation 0x34382172 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 34
20 CoreFoundation 0x34382116 __CFRunLoopDoSource1 + 138
21 CoreFoundation 0x34380f98 __CFRunLoopRun + 1384
22 CoreFoundation 0x342f3ebc CFRunLoopRunSpecific + 356
23 CoreFoundation 0x342f3d48 CFRunLoopRunInMode + 104
24 GraphicsServices 0x37eb72ea GSEventRunModal + 74
25 UIKit 0x36209300 UIApplicationMain + 1120
26 LiveTexOpClient 0x0002e144 main (main.m:14)
27 LiveTexOpClient 0x0002d28f start + 39
代码来自：
-(void)saveLatestSessionTimeStamp
{
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithDouble:[[NSDate date] timeIntervalSince1970]] forKey:self.savedLogin];
[[NSUserDefaults standardUserDefaults] synchronize];
}
崩溃仅发生在 5 个设备中的两个设备上。它出现在两个 iphone（ios 6.1.3）上，但没有出现在另一个 iphone 上（相同的 ios 6.1.3！）。任何人都可以帮助我吗？