我想使用以下代码呈现viewController。 由于其他一些原因，我需要在呈现控制器之前获得synchrolock。
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
LogInfo(@"get synchrolock On a background thread");
[RuiKlasseBaseViewController waitSemaphore];
dispatch_async(dispatch_get_main_queue(), ^{
LogInfo(@"presentViewController On main thread");
if (self.view.window) {
TeachingViewController*teachingController=[self.storyboard instantiateViewControllerWithIdentifier:@"Teaching"];
[self presentViewController:teachingController animated:YES completion:releaseSynchrolock];
} else {
LogInfo(@"release synchrolock");
[RuiKlasseBaseViewController signalSemaphore];
[self hidetital];
}
});
});
但有时在线上坠毁：
[self presentViewController:teachingController animated:YES completion:releaseSynchrolock];
崩溃日志：
Incident Identifier: B006117F-5F84-47B1-8B38-12BBD67D6383
CrashReporter Key: 95d234d099f2443ad742fad4e44bedb9c9dd5341
Hardware Model: iPad4,4
Process: MyApp [235]
Path: /private/var/mobile/Containers/Bundle/Application/C476541C-FA4B-479E-8744-18213785C697/MyApp.app/MyApp
Identifier: com.test.myapp
Version: 1180 (2.0.190)
Code Type: ARM-64 (Native)
Parent Process: launchd [1]
Date/Time: 2015-03-09 13:54:49.910 +0800
Launch Time: 2015-03-09 13:36:19.134 +0800
OS Version: iOS 8.1.2 (12B440)
Report Version: 105
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x00000000000000a4
Triggered by Thread: 15
Thread 0 name: Dispatch queue: com.apple.main-thread
Thread 0:
0 CoreFoundation 0x000000018538180c -[CFPrefsSearchListSource generationCountFromListOfSources:count:allowFetching:] + 112
1 CoreFoundation 0x0000000185381db8 -[CFPrefsSearchListSource alreadylocked_copyDictionary] + 152
2 CoreFoundation 0x0000000185381db8 -[CFPrefsSearchListSource alreadylocked_copyDictionary] + 152
3 CoreFoundation 0x0000000185380fcc -[CFPrefsSearchListSource alreadylocked_copyValueForKey:] + 44
4 CoreFoundation 0x000000018540f248 ___CFPreferencesCopyAppValueWithContainer_block_invoke + 68
5 CoreFoundation 0x0000000185380120 +[CFPrefsSearchListSource withSearchListForIdentifier:container:perform:] + 576
6 CoreFoundation 0x000000018540f1b8 _CFPreferencesCopyAppValueWithContainer + 196
7 Foundation 0x00000001861bdc28 -[NSUserDefaults(NSUserDefaults) objectForKey:] + 36
8 WebKitLegacy 0x0000000193f6e244 -[WebPreferences _valueForKey:] + 264
9 WebKitLegacy 0x0000000193f6e0ec -[WebPreferences _integerValueForKey:] + 24
10 WebKitLegacy 0x0000000193f749ec -[WebView(WebPrivate) _preferencesChanged:] + 5636
11 WebKitLegacy 0x0000000193f702d0 -[WebView(WebPrivate) _commonInitializationWithFrameName:groupName:] + 2332
12 WebKitLegacy 0x0000000193fe0ef4 -[WebView(WebPrivate) _initWithFrame:frameName:groupName:] + 148
13 UIKit 0x0000000189ce9f30 -[UIWebDocumentView initWithWebView:frame:] + 336
14 UIKit 0x0000000189ce9b88 -[UIWebBrowserView initWithWebView:frame:] + 52
15 UIKit 0x0000000189ce9ac8 -[UIWebBrowserView initWithFrame:] + 48
16 UIKit 0x0000000189f58d5c -[UIWebView _webViewCommonInitWithWebView:scalesPageToFit:] + 268
17 UIKit 0x0000000189f596e4 -[UIWebView initWithCoder:] + 120
18 UIKit 0x000000018a068d94 UINibDecoderDecodeObjectForValue + 808
19 UIKit 0x000000018a068a50 -[UINibDecoder decodeObjectForKey:] + 340
20 UIKit 0x0000000189f901b8 -[UIRuntimeConnection initWithCoder:] + 124
21 UIKit 0x000000018a068d94 UINibDecoderDecodeObjectForValue + 808
22 UIKit 0x000000018a068d34 UINibDecoderDecodeObjectForValue + 712
23 UIKit 0x000000018a068a50 -[UINibDecoder decodeObjectForKey:] + 340
24 UIKit 0x0000000189f8f640 -[UINib instantiateWithOwner:options:] + 1096
25 UIKit 0x0000000189e94270 -[UIViewController _loadViewFromNibNamed:bundle:] + 280
26 UIKit 0x0000000189b84840 -[UIViewController loadViewIfRequired] + 84
27 UIKit 0x0000000189b847ac -[UIViewController view] + 28
28 UIKit 0x000000018a275c30 -[_UIFullscreenPresentationController _setPresentedViewController:] + 72
29 UIKit 0x0000000189e7f1c4 -[UIPresentationController initWithPresentedViewController:presentingViewController:] + 116
30 UIKit 0x0000000189e9a264 -[UIViewController _presentViewController:withAnimationController:completion:] + 1968
31 UIKit 0x0000000189e9c67c __62-[UIViewController presentViewController:animated:completion:]_block_invoke + 116
32 UIKit 0x0000000189c71cec -[UIViewController presentViewController:animated:completion:] + 212
33 MyApp 0x00000001002a4438 __32-[LessonViewController shangke:]_block_invoke_2 (LessonViewController.m:656)
34 libdispatch.dylib 0x00000001964313a8 _dispatch_call_block_and_release + 20
35 libdispatch.dylib 0x0000000196431368 _dispatch_client_callout + 12
36 libdispatch.dylib 0x000000019643597c _dispatch_main_queue_callback_4CF + 928
37 CoreFoundation 0x0000000185389fa0 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 8
38 CoreFoundation 0x0000000185388048 __CFRunLoopRun + 1488
39 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
40 GraphicsServices 0x000000018e41b5a0 GSEventRunModal + 164
41 UIKit 0x0000000189bea3bc UIApplicationMain + 1484
42 MyApp 0x000000010024fc44 main (main.m:16)
43 libdyld.dylib 0x000000019645aa04 start + 0
Thread 1 name: Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0 libsystem_kernel.dylib 0x0000000196558c94 kevent64 + 8
1 libdispatch.dylib 0x000000019644097c _dispatch_mgr_invoke + 272
2 libdispatch.dylib 0x00000001964333b0 _dispatch_mgr_thread + 48
Thread 2 name: AFNetworking
Thread 2:
0 libsystem_kernel.dylib 0x0000000196558e7c mach_msg_trap + 8
1 libsystem_kernel.dylib 0x0000000196558cf4 mach_msg + 68
2 CoreFoundation 0x0000000185389ecc __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x0000000185387e20 __CFRunLoopRun + 936
4 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
5 Foundation 0x00000001861bd800 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 312
6 Foundation 0x0000000186217ef4 -[NSRunLoop(NSRunLoop) run] + 92
7 MyApp 0x00000001000c9398 +[AFURLConnectionOperation networkRequestThreadEntryPoint:] (AFURLConnectionOperation.m:193)
8 Foundation 0x00000001862a5c08 __NSThread__main__ + 1068
9 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
10 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
11 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 3 name: com.apple.NSURLConnectionLoader
Thread 3:
0 libsystem_kernel.dylib 0x0000000196558e7c mach_msg_trap + 8
1 libsystem_kernel.dylib 0x0000000196558cf4 mach_msg + 68
2 CoreFoundation 0x0000000185389ecc __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x0000000185387e20 __CFRunLoopRun + 936
4 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
5 CFNetwork 0x0000000184dba4e4 +[NSURLConnection(Loader) _resourceLoadLoop:] + 436
6 Foundation 0x00000001862a5c08 __NSThread__main__ + 1068
7 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
8 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
9 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 4 name: com.apple.CFSocket.private
Thread 4:
0 libsystem_kernel.dylib 0x0000000196573498 __select + 8
1 CoreFoundation 0x000000018538f8c4 __CFSocketManager + 656
2 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
3 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
4 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 5 name: WebThread
Thread 5:
0 libsystem_kernel.dylib 0x0000000196558e7c mach_msg_trap + 8
1 libsystem_kernel.dylib 0x0000000196558cf4 mach_msg + 68
2 CoreFoundation 0x0000000185389ecc __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x0000000185387e20 __CFRunLoopRun + 936
4 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
5 WebCore 0x00000001930ec854 RunWebThread(void*) + 464
6 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
7 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
8 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 6 name: JavaScriptCore::BlockFree
Thread 6:
0 libsystem_kernel.dylib 0x0000000196573078 __psynch_cvwait + 8
1 libsystem_pthread.dylib 0x000000019660efe0 _pthread_cond_wait + 620
2 libc++.1.dylib 0x0000000195580cac std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 52
3 JavaScriptCore 0x00000001868415f8 JSC::BlockAllocator::blockFreeingThreadMain() + 228
4 JavaScriptCore 0x000000018683cb7c WTF::wtfThreadEntryPoint(void*) + 20
5 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
6 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
7 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 7 name: JavaScriptCore::Marking
Thread 7:
0 libsystem_kernel.dylib 0x0000000196573078 __psynch_cvwait + 8
1 libsystem_pthread.dylib 0x000000019660efe0 _pthread_cond_wait + 620
2 libc++.1.dylib 0x0000000195580cac std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 52
3 JavaScriptCore 0x0000000186aea8b8 JSC::GCThread::waitForNextPhase() + 152
4 JavaScriptCore 0x0000000186aea95c JSC::GCThread::gcThreadMain() + 88
5 JavaScriptCore 0x000000018683cb7c WTF::wtfThreadEntryPoint(void*) + 20
6 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
7 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
8 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 8 name: WebCore: CFNetwork Loader
Thread 8:
0 libsystem_kernel.dylib 0x0000000196558e7c mach_msg_trap + 8
1 libsystem_kernel.dylib 0x0000000196558cf4 mach_msg + 68
2 CoreFoundation 0x0000000185389ecc __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x0000000185387e20 __CFRunLoopRun + 936
4 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
5 WebCore 0x0000000193120670 WebCore::runLoaderThread(void*) + 284
6 JavaScriptCore 0x000000018683cb7c WTF::wtfThreadEntryPoint(void*) + 20
7 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
8 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
9 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 9:
0 libsystem_kernel.dylib 0x0000000196558e7c mach_msg_trap + 8
1 libsystem_kernel.dylib 0x0000000196558cf4 mach_msg + 68
2 CoreFoundation 0x0000000185389ecc __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x0000000185387e20 __CFRunLoopRun + 936
4 CoreFoundation 0x00000001852b50a0 CFRunLoopRunSpecific + 392
5 CoreFoundation 0x00000001853071f8 CFRunLoopRun + 108
6 CoreMotion 0x0000000185cb298c 0x185c70000 + 272780
7 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
8 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
9 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 10:
0 libsystem_kernel.dylib 0x0000000196573c78 __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x000000019660d390 _pthread_wqthread + 988
2 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 11 name: Dispatch queue: cocoa.lumberjack
Thread 11:
0 libsystem_kernel.dylib 0x0000000196558eb8 semaphore_wait_trap + 8
1 libdispatch.dylib 0x000000019643ed98 _dispatch_group_wait_slow + 244
2 MyApp 0x0000000100137d18 +[DDLog lt_log:] (DDLog.m:665)
3 MyApp 0x0000000100136370 __40+[DDLog queueLogMessage:asynchronously:]_block_invoke (DDLog.m:286)
4 libdispatch.dylib 0x00000001964313a8 _dispatch_call_block_and_release + 20
5 libdispatch.dylib 0x0000000196431368 _dispatch_client_callout + 12
6 libdispatch.dylib 0x000000019643b4bc _dispatch_queue_drain + 1212
7 libdispatch.dylib 0x0000000196434470 _dispatch_queue_invoke + 128
8 libdispatch.dylib 0x000000019643d220 _dispatch_root_queue_drain + 660
9 libdispatch.dylib 0x000000019643e758 _dispatch_worker_thread3 + 104
10 libsystem_pthread.dylib 0x000000019660d2e0 _pthread_wqthread + 812
11 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 12 name: Dispatch queue: com.apple.root.default-qos.overcommit
Thread 12:
0 libsystem_kernel.dylib 0x0000000196573c78 __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x0000000196611838 _pthread_workqueue_addthreads + 60
2 libdispatch.dylib 0x000000019643cbf8 _dispatch_queue_wakeup_global_slow + 80
3 libdispatch.dylib 0x000000019643d1e4 _dispatch_root_queue_drain + 600
4 libdispatch.dylib 0x000000019643e758 _dispatch_worker_thread3 + 104
5 libsystem_pthread.dylib 0x000000019660d2e0 _pthread_wqthread + 812
6 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 13:
0 libsystem_kernel.dylib 0x0000000196573c78 __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x000000019660d390 _pthread_wqthread + 988
2 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 14 name: Dispatch queue: com.apple.root.default-qos
Thread 14:
0 libsystem_kernel.dylib 0x0000000196572420 __connect + 8
1 MyApp 0x00000001001e3d44 -[CommandSender sendUsingTCPForCommand:withObj:] (CommandSender.m:154)
2 MyApp 0x00000001001e3254 __47-[CommandSender sendCommandType:using:withObj:]_block_invoke (CommandSender.m:43)
3 libdispatch.dylib 0x00000001964313a8 _dispatch_call_block_and_release + 20
4 libdispatch.dylib 0x0000000196431368 _dispatch_client_callout + 12
5 libdispatch.dylib 0x000000019643d408 _dispatch_root_queue_drain + 1148
6 libdispatch.dylib 0x000000019643e758 _dispatch_worker_thread3 + 104
7 libsystem_pthread.dylib 0x000000019660d2e0 _pthread_wqthread + 812
8 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 15 Crashed:
0 QuartzCore 0x00000001894d67ec CA::Layer::collect_animations_(double, double*, CA::Layer::CollectAnimationsData*) + 76
1 QuartzCore 0x00000001894d6930 CA::Layer::collect_animations_(double, double*, CA::Layer::CollectAnimationsData*) + 400
2 QuartzCore 0x00000001894d6930 CA::Layer::collect_animations_(double, double*, CA::Layer::CollectAnimationsData*) + 400
3 QuartzCore 0x00000001894d6930 CA::Layer::collect_animations_(double, double*, CA::Layer::CollectAnimationsData*) + 400
4 QuartzCore 0x00000001894d6930 CA::Layer::collect_animations_(double, double*, CA::Layer::CollectAnimationsData*) + 400
5 QuartzCore 0x00000001894d6790 CA::Layer::collect_animations(CA::Transaction*, double, double*) + 36
6 QuartzCore 0x00000001894d406c CA::Context::commit_transaction(CA::Transaction*) + 1400
7 QuartzCore 0x00000001894d3988 CA::Transaction::commit() + 432
8 QuartzCore 0x0000000189504028 CA::Transaction::release_thread(void*) + 200
9 libsystem_pthread.dylib 0x000000019660e3dc _pthread_tsd_cleanup + 196
10 libsystem_pthread.dylib 0x000000019660e0a8 _pthread_exit + 136
11 libsystem_pthread.dylib 0x000000019660f32c pthread_exit + 40
12 Foundation 0x00000001861d6ffc +[NSThread exit] + 12
13 Foundation 0x00000001862a5c20 __NSThread__main__ + 1092
14 libsystem_pthread.dylib 0x000000019660fe7c _pthread_body + 160
15 libsystem_pthread.dylib 0x000000019660fdd8 _pthread_start + 156
16 libsystem_pthread.dylib 0x000000019660cfac thread_start + 0
Thread 16:
0 libsystem_kernel.dylib 0x0000000196573c78 __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x000000019660d390 _pthread_wqthread + 988
2 libsystem_pthread.dylib 0x000000019660cfa4 start_wqthread + 0
Thread 15 crashed with ARM Thread State (64-bit):
x0: 0x0000000000000000 x1: 0x000000014f939200 x2: 0x00000001063eb910 x3: 0x00000001063f3970
x4: 0x0000000003000001 x5: 0x0000000000000000 x6: 0x0000000000000000 x7: 0x0000000000000000
x8: 0x0000000000000001 x9: 0x0000000000000008 x10: 0x0000000000000001 x11: 0x0000000000004800
x12: 0x0000000000000000 x13: 0x0000000102a4d688 x14: 0x0000000000000000 x15: 0x0000000000000000
x16: 0x000000019657dd74 x17: 0x0000000195dffea0 x18: 0x0000000000000000 x19: 0x00000001063eb910
x20: 0x0000000000000004 x21: 0x00000001063eb718 x22: 0x0000000197313000 x23: 0x0000000000000000
x24: 0x0000000000000001 x25: 0x00000001063eb718 x26: 0x0000000102b4a084 x27: 0x0000000000000003
x28: 0x0000000000000001 fp: 0x00000001063eb6f0 lr: 0x00000001894d6934
sp: 0x00000001063eb650 pc: 0x00000001894d67ec cpsr: 0x20000000
非常感谢任何帮助。 感谢。