Xamarin：即使被抓住也无法处理NSException

时间：2017-05-01 18:44:27

标签： c# ios xamarin xamarin.ios xamarin.forms

我有一个有趣的问题，我正在捕捉异常（我在调试时遇到了“catch”断点）但是我的应用程序因以下代码中的未处理异常而崩溃：

        HttpResponseMessage response = null;
        try
        {
            response = await this.MyHttpClient.GetAsync( _url );
        }
        catch (Exception e)
        {
            System.Diagnostics.Debug.WriteLine(e);
        }

堆栈跟踪：

[0:] System.Net.WebException: The Internet connection appears to be offline. ---> Foundation.NSErrorException: Exception of type 'Foundation.NSErrorException' was thrown.
   --- End of inner exception stack trace ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in <54e129cad3ee4c61a6b46c3680ddc69a>:0 
  at ModernHttpClient.NativeMessageHandler+<SendAsync>c__async0.MoveNext () [0x002f8] in <a827d263b32642a294603e46fea01afb>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in <54e129cad3ee4c61a6b46c3680ddc69a>:0 
  at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:276 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () [0x00000] in <54e129cad3ee4c61a6b46c3680ddc69a>:0

缺少stackstrace是1行，它指的是包含“response = await this.MyHttpClient.GetAsync（_url）;”

的类/行

这怎么可能？ NSErrorException继承自Exception，因此应该被捕获 - 也就是说，因为如果我在catch块中放置一个断点，则会触发断点。到底是怎么回事？我很困惑。

编辑：通过在平台（iOS）而不是在PCL中捕获异常，我设法得到这个不是非常有用的堆栈跟踪：

An unhandled exception occured.

2017-05-01 21:07:47.940 MyAppiOS[319:30171] 
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
2017-05-01 21:07:47.940 MyAppiOS[319:30171] Unhandled managed exception:
Object reference not set to an instance of an object (System.NullReferenceException)
(null)
2017-05-01 21:07:47.941 MyAppiOS[319:30171] critical: Stacktrace:

2017-05-01 21:07:47.941 MyAppiOS[319:30171] critical: 
Native stacktrace:
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   0   MyAppiOS                            0x00000001000cd15c mono_handle_native_sigsegv + 256
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   1   libsystem_platform.dylib            0x000000018f539348 _sigtramp + 52
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   2   libsystem_pthread.dylib             0x000000018f53f450 pthread_kill + 112
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   3   libsystem_c.dylib                   0x000000018f3eb400 abort + 140
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   4   MyAppiOS                            0x00000001002012c0 xamarin_printf + 0
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   5   MyAppiOS                            0x0000000100111814 mono_invoke_unhandled_exception_hook + 132
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   6   MyAppiOS                            0x00000001000ccc60 mono_handle_exception_internal + 3784
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:   7   MyAppiOS                            0x00000001000cbd8c mono_handle_exception + 40
2017-05-01 21:07:48.138 MyAppiOS[319:30171] critical:
Failed to Stop app:  An error occured on client IDB44034 while executing a reply for topic xvs/idb/4.4.0.34/stop-app

EDIT2：忽略网络异常，这是一个分心和我错误的假设（将打印的异常误认为是实际的堆栈跟踪，但它不是 - 它只是打印）。只有第二个堆栈跟踪是相关的。 但是，我确实解决了这个问题！的种类。如果我在Mac上使用Xamarin Studio运行我的应用程序，则没有问题。只有当我使用Visual Studio和构建主机运行我的应用程序时问题仍然存在。两者都运行相同的，最新的，xamarin和mac os。非常奇怪......我确实设法找到了这个报告的错误：https://bugzilla.xamarin.com/show_bug.cgi?id=17419但是使用建议的解决方案无法取得成功。我现在只在Mac上运行我的应用程序。

0 个答案:

没有答案
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