我遇到了一个问题，还没有任何解决方案。在用户按下“主页”按钮后，我使用后台任务处理程序来启动一些数据获取。代码是这样的：
-(void)startRequest {
UIApplication *app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}];
//..
//Fetch data with NSURLRequest / delegate method
//..
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
if ([delegate respondsToSelector:delegateErrorMethod])
[delegate performSelector:delegateErrorMethod];
UIApplication *app = [UIApplication sharedApplication];
if (bgTask != UIBackgroundTaskInvalid) {
dispatch_async(dispatch_get_main_queue(), ^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
if([delegate respondsToSelector:delegateMethod])
[delegate performSelector:delegateMethod withObject:self];
UIApplication *app = [UIApplication sharedApplication];
if (bgTask != UIBackgroundTaskInvalid) {
dispatch_async(dispatch_get_main_queue(), ^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}
}
它工作得很好，但有时（没有任何问题或原因，所以它真的是不可预测的）应用程序崩溃，并显示以下崩溃日志：
Application Specific Information:
MyBackgroundTest[7745] has active assertions beyond permitted time:
{(
<SBProcessAssertion: 0x90e65e0> identifier: UIKitBackgroundCompletionTask process: MyBackgroundTest[7745] permittedBackgroundDuration: 600.000000 reason: finishTask owner pid:7745 preventSuspend preventIdleSleep
)}
Elapsed total CPU time (seconds): 0.010 (user 0.010, system 0.000), 100% CPU
Elapsed application CPU time (seconds): 0.000, 0% CPU
Thread 0:
0 libSystem.B.dylib 0x33b5d268 mach_msg_trap + 20
1 libSystem.B.dylib 0x33b5f354 mach_msg + 44
2 CoreFoundation 0x33a48648 __CFRunLoopServiceMachPort + 88
3 CoreFoundation 0x33a47ed2 __CFRunLoopRun + 350
4 CoreFoundation 0x33a47c80 CFRunLoopRunSpecific + 224
5 CoreFoundation 0x33a47b88 CFRunLoopRunInMode + 52
6 GraphicsServices 0x33b0e4a4 GSEventRunModal + 108
7 GraphicsServices 0x33b0e550 GSEventRun + 56
8 UIKit 0x32099322 -[UIApplication _run] + 406
9 UIKit 0x32096e8c UIApplicationMain + 664
10 MyBackgroundTest 0x00002d64 0x1000 + 7524
11 MyBackgroundTest 0x00002d18 0x1000 + 7448
Thread 1:
0 libSystem.B.dylib 0x33b89974 kevent + 24
1 libSystem.B.dylib 0x33c33704 _dispatch_mgr_invoke + 88
2 libSystem.B.dylib 0x33c33174 _dispatch_queue_invoke + 96
3 libSystem.B.dylib 0x33c32b98 _dispatch_worker_thread2 + 120
4 libSystem.B.dylib 0x33bd724a _pthread_wqthread + 258
5 libSystem.B.dylib 0x33bcf970 start_wqthread + 0
Thread 2:
0 libSystem.B.dylib 0x33b5d268 mach_msg_trap + 20
1 libSystem.B.dylib 0x33b5f354 mach_msg + 44
2 CoreFoundation 0x33a48648 __CFRunLoopServiceMachPort + 88
3 CoreFoundation 0x33a47ed2 __CFRunLoopRun + 350
4 CoreFoundation 0x33a47c80 CFRunLoopRunSpecific + 224
5 CoreFoundation 0x33a47b88 CFRunLoopRunInMode + 52
6 WebCore 0x304df124 RunWebThread(void*) + 332
7 libSystem.B.dylib 0x33bd6886 _pthread_start + 242
8 libSystem.B.dylib 0x33bcba88 thread_start + 0
Thread 3:
0 libSystem.B.dylib 0x33b5d268 mach_msg_trap + 20
1 libSystem.B.dylib 0x33b5f354 mach_msg + 44
2 CoreFoundation 0x33a48648 __CFRunLoopServiceMachPort + 88
3 CoreFoundation 0x33a47ed2 __CFRunLoopRun + 350
4 CoreFoundation 0x33a47c80 CFRunLoopRunSpecific + 224
5 CoreFoundation 0x33a47b88 CFRunLoopRunInMode + 52
6 Foundation 0x336465f6 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 206
7 Foundation 0x33624192 -[NSThread main] + 38
8 Foundation 0x3361d242 __NSThread__main__ + 966
9 libSystem.B.dylib 0x33bd6886 _pthread_start + 242
10 libSystem.B.dylib 0x33bcba88 thread_start + 0
Thread 4:
0 libSystem.B.dylib 0x33b8168c select$DARWIN_EXTSN + 20
1 CoreFoundation 0x33a7f662 __CFSocketManager + 582
2 libSystem.B.dylib 0x33bd6886 _pthread_start + 242
3 libSystem.B.dylib 0x33bcba88 thread_start + 0
Thread 5:
0 libSystem.B.dylib 0x33bd79e0 __workq_kernreturn + 8
1 libSystem.B.dylib 0x33bd7364 _pthread_wqthread + 540
2 libSystem.B.dylib 0x33bcf970 start_wqthread + 0
Thread 6:
0 libSystem.B.dylib 0x33bd79e0 __workq_kernreturn + 8
1 libSystem.B.dylib 0x33bd7364 _pthread_wqthread + 540
2 libSystem.B.dylib 0x33bcf970 start_wqthread + 0
Unknown thread crashed with unknown flavor: 5, state_count: 1
UPDATE:似乎与此问题相关的更密切的线程已打开here。
该错误与重定向 http 连接、异步和同步 NRURL 操作有关。也许，既然 NSURLConnection 继承自基础框架，那么这个 bug 也存在于 iPhone 上吗？
打开雷达：1062401
我的调查表明，无论真正的原因是什么，您都会遇到以下异常：
TMS[13544] has active assertions beyond permitted time:
{(
<SBProcessAssertion: 0x8cb6040> identifier: UIKitBackgroundCompletionTask process: TMS[13544] permittedBackgroundDuration: 600.000000 reason: finishTask owner pid:13544 preventSuspend preventIdleSleep
)}
如果代码没有执行`endBackgroundTask:'方法。
这意味着创建的每个后台任务beginBackgroundTaskWithExpirationHandler:' call MUST be ended with结束后台任务：'。
仔细检查“endBackgroundTask:”是否使用正确的任务 ID 调用。
本文内容由网友自发贡献，版权归原作者所有，本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容，请联系:hwhale#tublm.com(使用前将#替换为@)
