title: Cannot enable AppCenter.Crashes on Xamarin.iOS app
body: <p>Trying to use the new AppCenter on an existing Xamarin.iOS application, i have some trouble with the AppCenter.Crashes API.</p>
  
  <p>I follow the Get started section and add following code in my AppDelegate.cs : </p>
  
  <pre><code>using Microsoft.AppCenter;
  using Microsoft.AppCenter.Analytics;
  using Microsoft.AppCenter.Crashes;
  
  // ...
  public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
  {
      //...
      // App Center
      AppCenter.Start("xxxxxxx-xxxx-xxxx-xxxx", typeof(Analytics), typeof(Crashes));
  
      return true;
  }
  </code></pre>
  
  <p>I also installed corresponding NuGet packages (here is corresponding line in my packages.config)</p>
  
  <pre><code>&lt;package id="Microsoft.AppCenter" version="1.5.0" targetFramework="xamarinios10" /&gt;
  &lt;package id="Microsoft.AppCenter.Analytics" version="1.5.0" targetFramework="xamarinios10" /&gt;
  &lt;package id="Microsoft.AppCenter.Crashes" version="1.5.0" targetFramework="xamarinios10" /&gt;
  </code></pre>
  
  <p>Note that If i disable the AppCenter.Crashes module :</p>
  
  <pre><code>AppCenter.Start("xxxxxxx-xxxx-xxxx-xxxx", typeof(Analytics));
  </code></pre>
  
  <p>Everything is fine (and i can see Analytics in the App center back-end)</p>
  
  <p>But with the AppCenter.Crashes module enable, my app crash with the following message in console : </p>
  
  <pre><code>11:24:53.521334 +0100   MyApp.iOS   [AppCenter] VERBOSE: +[MSAppDelegateForwarder addTraceBlock:]_block_invoke_2/101 Start buffering traces.
  11:24:53.521381 +0100   MyApp.iOS   [AppCenter] DEBUG: +[MSAppDelegateForwarder load]_block_invoke/48 Application delegate forwarder is enabled. It may use swizzling.
  11:24:53.521587 +0100   MyApp.iOS   [AppCenter] VERBOSE: +[MSAppDelegateForwarder flushTraceBuffer]/398 Stop buffering traces, flushed.
  11:24:53.524550 +0100   MyApp.iOS   [AppCenterXamarin] DEBUG: +[MSWrapperLogger MSWrapperLog:tag:level:]/7 No named identifier found in appSecret; using as-is
  11:24:53.528625 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes fileURLWithName:]/1075 Didn't create crash buffer file as one already existed at file:///var/mobile/Containers/Data/Application/76272998-91E2-469F-9A0F-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/0.mscrasheslogbuffer.
  11:24:53.529190 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes fileURLWithName:]/1075 Didn't create crash buffer file as one already existed at file:///var/mobile/Containers/Data/Application/76272998-91E2-469F-9A0F-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/1.mscrasheslogbuffer.
  11:24:53.529652 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes fileURLWithName:]/1075 Didn't create crash buffer file as one already existed at file:///var/mobile/Containers/Data/Application/76272998-91E2-469F-9A0F-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/2.mscrasheslogbuffer.
  11:24:53.529787 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes fileURLWithName:]/1075 Didn't create crash buffer file as one already existed at file:///var/mobile/Containers/Data/Application/76272998-91E2-469F-9A0F-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/3.mscrasheslogbuffer.
  11:24:53.547125 +0100   MyApp.iOS   [AppCenter] INFO: -[MSHttpSender networkStateChanged]/346 Internet connection is up.
  11:24:53.549737 +0100   MyApp.iOS   [AppCenter] DEBUG: +[MSSessionContext sharedInstance]_block_invoke/31 5 session(s) in the history.
  11:24:53.551565 +0100   MyApp.iOS   [AppCenter] VERBOSE: -[MSSessionContext setSessionId:]/70 Stored new session with id:(null) and timestamp: 2018-03-14 10:24:53 +0000.
  11:24:53.551644 +0100   MyApp.iOS   [AppCenter] INFO: -[MSAppCenter configure:]/222 App Center SDK configured successfully.
  11:24:53.551699 +0100   MyApp.iOS   [AppCenter] VERBOSE: -[MSAppCenter start:withServices:]/234 Prepare to start services: MSAnalytics, MSCrashes
  11:24:53.551865 +0100   MyApp.iOS   [AppCenter] VERBOSE: -[MSAppCenter start:withServices:]/236 Start services MSCrashes, MSAnalytics
  11:24:53.552616 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes configureCrashReporterWithUncaughtExceptionHandlerEnabled:]/588 EnableUncaughtExceptionHandler is set to YES
  11:24:53.557629 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes configureCrashReporterWithUncaughtExceptionHandlerEnabled:]/639 Exception handler successfully initialized.
  11:24:53.574825 +0100   MyApp.iOS   [AppCenterCrashes] INFO: -[MSCrashes applyEnabledState:]/357 Crashes service has been enabled.
  11:24:53.578904 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes startWithChannelGroup:appSecret:]/401 Started crash service.
  11:24:53.579845 +0100   MyApp.iOS   [AppCenter] VERBOSE: -[MSSessionContext setSessionId:]/70 Stored new session with id:36C20159-XXXX-XXXX-XXXX-1E137546055A and timestamp: 2018-03-14 10:24:53 +0000.
  11:24:53.579893 +0100   MyApp.iOS   [AppCenterAnalytics] INFO: -[MSSessionTracker renewSessionId]/50 New session ID: 36C20159-XXXX-XXXX-XXXX-1E137546055A
  11:24:53.579940 +0100   MyApp.iOS   CCMonitor created
  11:24:53.584290 +0100   MyApp.iOS   [AppCenterAnalytics] INFO: -[MSAnalytics applyEnabledState:]/108 Analytics service has been enabled.
  11:24:53.585392 +0100   MyApp.iOS   [AppCenterAnalytics] VERBOSE: -[MSAnalytics startWithChannelGroup:appSecret:]/73 Started Analytics service.
  11:24:53.586034 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes onEnqueuingLog:withInternalId:]/448 Storing a log to Crashes Buffer: (sid: 36C20159-XXXX-XXXX-XXXX-1E137546055A, type: startSession)
  11:24:53.586103 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes onEnqueuingLog:withInternalId:]/459 Found an empty buffer position.
  11:24:53.586193 +0100   MyApp.iOS   [AppCenter] DEBUG: -[MSChannelUnitDefault enqueueItem:]_block_invoke/114 Saving log, type: startSession.
  11:24:53.589925 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes deleteBufferedLog:withInternalId:]/520 Deleting a log from buffer with id ED4281FF-XXXX-XXXX-BB26-4DF6975F55EC
  11:24:53.590438 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes onEnqueuingLog:withInternalId:]/448 Storing a log to Crashes Buffer: (sid: (null), type: startService)
  11:24:53.590495 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes onEnqueuingLog:withInternalId:]/459 Found an empty buffer position.
  11:24:53.590541 +0100   MyApp.iOS   [AppCenter] DEBUG: -[MSChannelUnitDefault enqueueItem:]_block_invoke/114 Saving log, type: startService.
  11:24:53.592715 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes deleteBufferedLog:withInternalId:]/520 Deleting a log from buffer with id 5B6ECE02-XXXX-XXXX-86F8-10C663A6C411
  11:24:53.603916 +0100   MyApp.iOS   [MyApp.iOS][DEBUG] iPhone format detected
  11:24:54.674171 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes startCrashProcessing]/695 Start delayed CrashManager processing
  11:24:54.757002 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes processCrashReports]/755 Crash reports found
  11:24:54.770674 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes processCrashReports]/767 shouldProcessErrorReport is not implemented or returned YES, processing the crash report: &lt;MSPLCrashReport: 0x1c00a6240&gt;
  11:24:54.770755 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes processCrashReports]/755 Crash reports found
  11:24:54.779793 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes processCrashReports]/767 shouldProcessErrorReport is not implemented or returned YES, processing the crash report: &lt;MSPLCrashReport: 0x1d42bd0a0&gt;
  11:24:54.779905 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes processCrashReports]/755 Crash reports found
  11:24:54.787919 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes processCrashReports]/767 shouldProcessErrorReport is not implemented or returned YES, processing the crash report: &lt;MSPLCrashReport: 0x1d44a2e80&gt;
  11:24:54.787956 +0100   MyApp.iOS   [AppCenterCrashes] VERBOSE: -[MSCrashes processCrashReports]/755 Crash reports found
  11:24:54.794906 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: -[MSCrashes processCrashReports]/767 shouldProcessErrorReport is not implemented or returned YES, processing the crash report: &lt;MSPLCrashReport: 0x1d44a8820&gt;
  17:55:19.480297 +0100   MyApp.iOS   [MyApp.iOS][DEBUG] api Sync success, need to write now ....  &lt;- My app debug message, all is OK here
  17:55:19.482483 +0100   MyApp.iOS   [MyApp.iOS][DEBUG] 0 total objects received .... &lt;- My app debug message, all is OK here
  17:38:55.495458 +0100   MyApp.iOS   dynamic_cast error 2: One or more of the following type_info's  has hidden visibility.  They should all have public visibility.   N10__cxxabiv116__shim_type_infoE, id, N10__cxxabiv117__pbase_type_infoE.
  17:38:55.495535 +0100   MyApp.iOS   dynamic_cast error 2: One or more of the following type_info's  has hidden visibility.  They should all have public visibility.   N10__cxxabiv116__shim_type_infoE, id, N10__cxxabiv117__pbase_type_infoE.
  17:38:55.495594 +0100   MyApp.iOS   dynamic_cast error 2: One or more of the following type_info's  has hidden visibility.  They should all have public visibility.   N10__cxxabiv116__shim_type_infoE, id, N10__cxxabiv117__pbase_type_infoE.
  11:25:01.376121 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: void ms_save_log_buffer_callback(siginfo_t *, ucontext_t *, void *)/102 Closed a buffer file: /var/mobile/Containers/Data/Application/76272998-XXXX-XXXX-XXXX-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/0.mscrasheslogbuffer
  11:25:01.376170 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: void ms_save_log_buffer_callback(siginfo_t *, ucontext_t *, void *)/102 Closed a buffer file: /var/mobile/Containers/Data/Application/76272998-XXXX-XXXX-XXXX-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/1.mscrasheslogbuffer
  11:25:01.376292 +0100   MyApp.iOS   [AppCenterCrashes] DEBUG: void ms_save_log_buffer_callback(siginfo_t *, ucontext_t *, void *)/102 Closed a buffer file: /var/mobile/Containers/Data/Application/76272998-XXXX-XXXX-XXXX-9B0C7A9899E1/Library/Caches/com.microsoft.appcenter/crasheslogbuffer/2.mscrasheslogbuffer
  </code></pre>
  
  <p><em>Last logs are repeated from <code>1.mscrasheslogbuffer</code> to <code>59.mscrasheslogbuffer</code></em></p>
  
  <p>Note that my app loading follow this steps : </p>
  
  <ul>
  <li>Loading a first viewController with an image, an activity indicator
  whitch calls some Rest API</li>
  <li>After API calls perform a segue to another ViewController with a NavBar</li>
  </ul>
  
  <p>App seems crash between the two step : I can see the first screen and log indicate that the http/api stuff is OK.</p>
  
  <p>Note that i have the same behavior on a simulator and a real device.</p>
  
  <p>Any ideas ?</p>
  
  <p><strong>Edit 1</strong> : Add more logs with <code>AppCenter.LogLevel = LogLevel.Verbose;</code></p>