我在Swift中编写了一个应用程序，当处于低功耗模式时会在以下行中崩溃。它基本上是在后台线程上运行的请求。以及在主线程上发生的一些UI更新。
在低功耗模式下，我无法在手机上重新创建崩溃，但据我的用户说，这是根本原因。
// Run the request on a background thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
self.runRequestOnBackgroundThread(request)
});
func runRequestOnBackgroundThread(request: NSMutableURLRequest) {
//We need to update the UI on the mainthread/ ONLY THE UI
dispatch_async(dispatch_get_main_queue(), {
self.scanInProgress()
})
let session = NSURLSession.sharedSession()
// run the request
let task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
self.analyzeResults(data!)
})
task.resume()
}
func analyzeResults(dataToParse: NSData) {
// Update UI on the main thread and analyze data from request
// Line 491 below this line
dispatch_async(dispatch_get_main_queue(), {
//Here goes some regex
})
我也在Apple.com上找到了这个：
希望延长iPhone电池续航时间的用户可以启用Low 设置下的电源模式＆gt;电池。在低功耗模式下，iOS可以保留 通过采取某些节能措施来延长电池寿命。例如， 系统可能：
- 降低CPU和GPU性能
- 暂停自行决定和背景活动，包括网络
- 降低屏幕亮度
- 减少自动锁定设备的超时
- 禁用邮件提取
- 禁用动作效果
- 停用动画壁纸
声音问题是暂停自行决定和后台活动，包括网络？
如何启用低功耗模式（我有一些UIView.animateWithDuration），我如何在后台发出请求并同时更新主线程上的UI？当这些方法运行时，用户将始终将应用程序置于前台，这是否意味着我应该在主线程上运行请求？
以下是Fabric / Crashlytics的崩溃报告：
#-1. com.apple.main-thread
0 libsystem_platform.dylib 0x18428d8b0 _platform_memcmp + 32
1 CoreFoundation 0x1845fe710 __CFStringEqual + 256
2 CoreFoundation 0x1845fe710 __CFStringEqual + 256
3 CoreFoundation 0x18450ebf4 CFEqual + 400
4 CoreFoundation 0x184670314 __NSCacheKeyEqual + 12
5 libcache.dylib 0x184006bcc _entry_get_optionally_checking_collisions + 164
6 libcache.dylib 0x1840051b8 cache_get_and_retain + 132
7 CoreFoundation 0x18455f22c -[NSCache objectForKey:] + 68
8 CoreUI 0x189146660 -[CUIStructuredThemeStore _canGetRenditionWithKey:isFPO:lookForSubstitutions:] + 360
9 CoreUI 0x189168f48 -[CUICatalog _resolvedRenditionKeyFromThemeRef:withBaseKey:scaleFactor:deviceIdiom:deviceSubtype:sizeClassHorizontal:sizeClassVertical:memoryClass:graphicsClass:graphicsFallBackOrder:] + 1416
10 CoreUI 0x1891680fc -[CUICatalog namedLookupWithName:scaleFactor:deviceIdiom:deviceSubtype:sizeClassHorizontal:sizeClassVertical:] + 148
11 UIKit 0x189b7d994 __98-[_UIAssetManager imageNamed:scale:idiom:subtype:cachingOptions:sizeClassPair:attachCatalogImage:]_block_invoke + 424
12 UIKit 0x189b7d734 -[_UIAssetManager imageNamed:scale:idiom:subtype:cachingOptions:sizeClassPair:attachCatalogImage:] + 212
13 UIKit 0x189c90584 -[UIImageAsset imageWithTraitCollection:] + 404
14 UIKit 0x1896cf058 -[UIImageView _resolveImageForTrait:] + 460
15 UIKit 0x1896ce928 -[UIImageView _didMoveFromWindow:toWindow:] + 212
16 UIKit 0x18931ad7c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 760
17 UIKit 0x1893a04f8 -[UIControl _didMoveFromWindow:toWindow:] + 80
18 UIKit 0x18931ad7c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 760
19 UIKit 0x18931a310 __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke + 152
20 Foundation 0x184f4d500 -[NSISEngine withBehaviors:performModifications:] + 168
21 UIKit 0x18931a194 -[UIView(Hierarchy) _postMovedFromSuperview:] + 532
22 UIKit 0x189327b80 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1784
23 UIKit 0x189420b34 -[UITransitionView transition:fromView:toView:removeFromView:] + 1544
24 UIKit 0x189420458 -[UIViewControllerBuiltinTransitionViewAnimator animateTransition:] + 2780
25 UIKit 0x18967ab7c __56-[UIPresentationController runTransitionForCurrentState]_block_invoke + 2228
26 UIKit 0x1895d0b70 _runAfterCACommitDeferredBlocks + 292
27 UIKit 0x1895de030 _cleanUpAfterCAFlushAndRunDeferredBlocks + 92
28 UIKit 0x189311c24 _afterCACommitHandler + 96
29 CoreFoundation 0x1845e4588 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
30 CoreFoundation 0x1845e232c __CFRunLoopDoObservers + 372
31 CoreFoundation 0x1845e275c __CFRunLoopRun + 928
32 CoreFoundation 0x184511680 CFRunLoopRunSpecific + 384
33 GraphicsServices 0x185a20088 GSEventRunModal + 180
34 UIKit 0x189388d90 UIApplicationMain + 204
35 TestDrive 0x1000a32ec main (AppDelegate.swift:15)
36 libdispatch.dylib 0x1840b28b8 (Missing)
#0. com.apple.libdispatch-manager
0 libsystem_kernel.dylib 0x1841d14fc kevent_qos + 8
1 libdispatch.dylib 0x18409494c _dispatch_mgr_invoke + 232
2 libdispatch.dylib 0x1840837bc _dispatch_source_invoke + 50
#1. com.twitter.crashlytics.ios.MachExceptionServer
0 TestDrive 0x1000d94c8 CLSProcessRecordAllThreads + 4296103112
1 TestDrive 0x1000d94c8 CLSProcessRecordAllThreads + 4296103112
2 TestDrive 0x1000d98e8 CLSProcessRecordAllThreads + 4296104168
3 TestDrive 0x1000ca5a8 CLSHandler + 4296041896
4 TestDrive 0x1000c572c CLSMachExceptionServer + 4296021804
5 libsystem_pthread.dylib 0x184297b28 _pthread_body + 156
6 libsystem_pthread.dylib 0x184297a8c _pthread_body + 154
7 libsystem_pthread.dylib 0x184295028 thread_start + 4
#2. com.apple.NSURLConnectionLoader
0 libsystem_kernel.dylib 0x1841b54bc mach_msg_trap + 8
1 libsystem_kernel.dylib 0x1841b5338 mach_msg + 72
2 CoreFoundation 0x1845e4ac0 __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x1845e27c4 __CFRunLoopRun + 1032
4 CoreFoundation 0x184511680 CFRunLoopRunSpecific + 384
5 CFNetwork 0x184c81434 +[NSURLConnection(Loader) _resourceLoadLoop:] + 412
6 Foundation 0x184fefc40 __NSThread__start__ + 1000
7 libsystem_pthread.dylib 0x184297b28 _pthread_body + 156
8 libsystem_pthread.dylib 0x184297a8c _pthread_body + 154
9 libsystem_pthread.dylib 0x184295028 thread_start + 4
#3. com.apple.CFSocket.private
0 libsystem_kernel.dylib 0x1841d0368 __select + 8
1 CoreFoundation 0x1845eb028 __CFSocketManager + 648
2 libsystem_pthread.dylib 0x184297b28 _pthread_body + 156
3 libsystem_pthread.dylib 0x184297a8c _pthread_body + 154
4 libsystem_pthread.dylib 0x184295028 thread_start + 4
#4. com.apple.coremedia.player.async
0 libsystem_kernel.dylib 0x1841b54f8 semaphore_wait_trap + 8
1 libdispatch.dylib 0x18409255c _dispatch_semaphore_wait_slow + 244
2 MediaToolbox 0x18a119454 fpa_AsyncMovieControlThread + 1948
3 CoreMedia 0x1865ea980 figThreadMain + 272
4 libsystem_pthread.dylib 0x184297b28 _pthread_body + 156
5 libsystem_pthread.dylib 0x184297a8c _pthread_body + 154
6 libsystem_pthread.dylib 0x184295028 thread_start + 4
#5. com.apple.CoreMotion.MotionThread
0 libsystem_kernel.dylib 0x1841b54bc mach_msg_trap + 8
1 libsystem_kernel.dylib 0x1841b5338 mach_msg + 72
2 CoreFoundation 0x1845e4ac0 __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x1845e27c4 __CFRunLoopRun + 1032
4 CoreFoundation 0x184511680 CFRunLoopRunSpecific + 384
5 CoreFoundation 0x18455ee2c CFRunLoopRun + 112
6 CoreMotion 0x18a03e22c (null) + 95286384
7 libsystem_pthread.dylib 0x184297b28 _pthread_body + 156
8 libsystem_pthread.dylib 0x184297a8c _pthread_body + 154
9 libsystem_pthread.dylib 0x184295028 thread_start + 4
#6. Thread
0 libsystem_kernel.dylib 0x1841d0b6c __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x184295530 _pthread_wqthread + 1284
2 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
#7. com.apple.camera.avcapturesession
0 libsystem_kernel.dylib 0x1841b54bc mach_msg_trap + 8
1 libsystem_kernel.dylib 0x1841b5338 mach_msg + 72
2 CoreFoundation 0x1845e4ac0 __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x1845e27c4 __CFRunLoopRun + 1032
4 CoreFoundation 0x184511680 CFRunLoopRunSpecific + 384
5 AVFoundation 0x18a8e61dc -[AVRunLoopCondition _waitInMode:untilDate:] + 432
6 AVFoundation 0x18a8ce960 -[AVCaptureSession _stopFigCaptureSession] + 412
7 AVFoundation 0x18a8ceb34 -[AVCaptureSession _setRunning:] + 216
8 CameraKit 0x18d1dcce0 __35-[CMKCaptureController stopPreview]_block_invoke
9 libdispatch.dylib 0x184081630 _dispatch_call_block_and_release + 24
10 libdispatch.dylib 0x1840815f0 _dispatch_client_callout + 16
11 libdispatch.dylib 0x18408d634 _dispatch_queue_drain + 864
12 libdispatch.dylib 0x1840850f4 _dispatch_queue_invoke + 464
13 libdispatch.dylib 0x1840815f0 _dispatch_client_callout + 16
14 libdispatch.dylib 0x18408fa88 _dispatch_root_queue_drain + 2140
15 libdispatch.dylib 0x18408f224 _dispatch_worker_thread3 + 112
16 libsystem_pthread.dylib 0x184295470 _pthread_wqthread + 1092
17 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
Crashed: NSOperationQueue 0x15d5754b0 :: NSOperation 0x15e9b8460 (QOS: LEGACY)
0 TestDrive 0x1000b597c VerifyDriverViewController.(runRequestOnBackgroundThread(NSMutableURLRequest) -> ()).(closure #2) (VerifyDriverViewController.swift:491)
1 CFNetwork 0x184c0f344 __75-[__NSURLSessionLocal taskForClass:request:uploadFile:bodyData:completion:]_block_invoke + 32
2 CFNetwork 0x184c21cc4 __49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke + 296
3 Foundation 0x184fd4334 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 16
4 Foundation 0x184f27100 -[NSBlockOperation main] + 96
5 Foundation 0x184f17348 -[__NSOperationInternal _start:] + 604
6 Foundation 0x184fd6728 __NSOQSchedule_f + 224
7 libdispatch.dylib 0x1840815f0 _dispatch_client_callout + 16
8 libdispatch.dylib 0x18408d634 _dispatch_queue_drain + 864
9 libdispatch.dylib 0x1840850f4 _dispatch_queue_invoke + 464
10 libdispatch.dylib 0x18408f504 _dispatch_root_queue_drain + 728
11 libdispatch.dylib 0x18408f224 _dispatch_worker_thread3 + 112
12 libsystem_pthread.dylib 0x184295470 _pthread_wqthread + 1092
13 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
#9. Thread
0 libsystem_kernel.dylib 0x1841d0b6c __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x184295530 _pthread_wqthread + 1284
2 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
#10. Thread
0 libsystem_kernel.dylib 0x1841d0b6c __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x184295530 _pthread_wqthread + 1284
2 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
#11. Thread
0 libsystem_kernel.dylib 0x1841d0b6c __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x184295530 _pthread_wqthread + 1284
2 libsystem_pthread.dylib 0x184295020 start_wqthread + 4
答案 0 :(得分：0)
这是导致崩溃的线程的堆栈跟踪顶部：
Crashed: NSOperationQueue 0x15d5754b0 :: NSOperation 0x15e9b8460 (QOS: LEGACY)
0 TestDrive 0x1000b597c VerifyDriverViewController.(runRequestOnBackgroundThread(NSMutableURLRequest) -> ()).(closure #2) (VerifyDriverViewController.swift:491)
1 CFNetwork 0x184c0f344 __75-[__NSURLSessionLocal taskForClass:request:uploadFile:bodyData:completion:]_block_invoke + 32
...
看起来崩溃发生在以下闭包内：
{ data, response, error -> Void in
self.analyzeResults(data!)
}
但在进入 analyzeResults(dataToParse: NSData) 函数之前。 self.analyzeResults(data!) 行唯一明显的问题是您在未检查它是否存在的情况下强制解包 data。
如您所见，Apple 提到在低功耗模式下系统可能会：
<块引用>暂停自主活动和后台活动，包括社交
因此，可能是因为您的用户的低功耗模式网络暂停，导致网络请求超时。由于这些超时，您的 data 变量变为 nil，然后您会崩溃。