iOS7：后台任务(“myapp”在超出允许时间后有活动断言)

崩溃报告详情：

Hardware Model:      iPhone5,2
Exception Type:  00000020
Exception Codes: 0x000000008badf00d
Highlighted Thread:  3

Application Specific Information:
MyApp[1369] has active assertions beyond permitted time: 
{(
<BKProcessAssertion: 0x175ca7d0> identifier: Called by MyApp, from -[AppDelegate applicationDidEnterBackground:] process: MyApp[1369] permittedBackgroundDuration: 180.000000 reason: finishTask owner pid:1369 preventSuspend  preventIdleSleep      preventSuspendOnSleep 
)}

线程3：

Thread 3 name:  com.apple.NSURLConnectionLoader
Thread 3:
0   libsystem_kernel.dylib          0x3937ea50 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x3937e848 mach_msg + 36
2   CoreFoundation                  0x2e61261c __CFRunLoopServiceMachPort + 152
3   CoreFoundation                  0x2e610d3c __CFRunLoopRun + 788
4   CoreFoundation                  0x2e57b7a4 CFRunLoopRunSpecific + 520
5   CoreFoundation                  0x2e57b586 CFRunLoopRunInMode + 102
6   Foundation                      0x2efbb23c +[NSURLConnection(Loader)     _resourceLoadLoop:] + 316
7   Foundation                      0x2f030a0a __NSThread__main__ + 1058
8   libsystem_pthread.dylib         0x393f8956 _pthread_body + 138
9   libsystem_pthread.dylib         0x393f88c6 _pthread_start + 98
10  libsystem_pthread.dylib         0x393f6ae4 thread_start + 4

我的应用程序在“applicationDidEnterBackground”使用此代码的后台任务：

// 10min background task
UIBackgroundTaskIdentifier myLongTask;
myLongTask = [[UIApplication sharedApplication]
              beginBackgroundTaskWithExpirationHandler:^{
                  [locationMgrInstance timerSet];
              }];
// cell change  
[locationMgrInstance startMonitoringSignificantLocationChanges];

它适用于iOS 6 ……但是！ iOS 7在180秒后抛出断言.
救命！

此消息表明您的后台任务运行时间过长. iOS7改变了后台处理的某些方面.特别是后台任务应该在很短的时间内完成,如果没有,你的应用程序就会被终止.您需要了解后台任务的运行方式.特别是,您需要确保调用[[UIApplication sharedApplication] endBackgroundTask：task];及时.您还应该在到期处理程序中调用此方法.

查看Apple iOS App Programming Guide Background Execution Guide中的后台执行和多任务部分.

此外,您可以检查[[UIApplication sharedApplication] backgroundTimeRemaining] – 在iOS 6上,此时间为10分钟.在iOS 7中它从3分钟开始 – 这就是为什么你在180秒后超时的原因.您需要重新评估您的背景策略以处理新限制.