ios崩溃[\u UIBackgroundTaskInfo fireExpirationHandler]

从crashlytics那里得到了坠机报告，知道怎么破译吗？我想这和我正在做的一些背景工作有关。我正在使用restkit的后台继续选项。Crashlytics还告诉我，当这种情况发生时，只有12%的用户关注该应用程序

0    libobjc.A.dylib    objc_msgSend + 15
1    UIKit ✭            -[_UIBackgroundTaskInfo fireExpirationHandler] + 48
2    UIKit              -[UIApplication handleEvent:withNewEvent:] + 1288
3    UIKit              -[UIApplication sendEvent:] + 54
4    UIKit              _UIApplicationHandleEvent + 5826
5    GraphicsServices   PurpleEventCallback + 882
6    CoreFoundation     __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 38
7    CoreFoundation     __CFRunLoopDoSource1 + 140
8    CoreFoundation     __CFRunLoopRun + 1370
9    CoreFoundation     CFRunLoopRunSpecific + 300
10   CoreFoundation     CFRunLoopRunInMode + 104
11   GraphicsServices   GSEventRunModal + 136
12   UIKit              UIApplicationMain + 1080