Xamarin iOS app SIGSEGV - ios

Question

I am getting occasional SIGSEGV errors like below in my app (c# Xamarin iOS app with latest version of Xamarin Studio=5.8.3, Xamarin.iOS=8.9.1.3
It looks like in crashed in UIKit and from my own app "ObymobiMobileAppiOS" it's just in "main".
What kind of problem it is?
How can I get more info or debug it?
I can reproduce it by using the app for about 5 mins.
Stacktrace:
at <unknown> <0xffffffff>
at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <0xffffffff>
at UIKit.UIApplication.Main (string[],intptr,intptr) [0x00005] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:62
at UIKit.UIApplication.Main (string[],string,string) [0x0001c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:45
at Obymobi.Mobile.App.iOS.Application.Main (string[]) [0x000b9] in /Users/billbatchelor/Documents/Mobile Development/AllInOne/Obymobi.Xamarin/Obymobi.Mobile.App.iOS/Main.cs:52
at (wrapper runtime-invoke) object.runtime_invoke_dynamic (intptr,intptr,intptr,intptr) <0xffffffff>
Native stacktrace:
0 ObymobiMobileAppiOS 0x00000001024ef9ac mono_handle_native_sigsegv + 264
1 ObymobiMobileAppiOS 0x00000001024f97cc mono_sigsegv_signal_handler + 316
2 libsystem_platform.dylib 0x000000019890895c _sigtramp + 68
3 UIKit 0x000000018b535540 <redacted> + 216
4 UIKit 0x000000018b535030 <redacted> + 452
5 UIKit 0x000000018b534e38 <redacted> + 216
6 UIKit 0x000000018b534d4c <redacted> + 468
7 UIKit 0x000000018b48fd8c <redacted> + 264
8 UIKit 0x000000018b32ca2c <redacted> + 700
9 UIKit 0x000000018b325f68 <redacted> + 684
10 UIKit 0x000000018b2f918c <redacted> + 264
11 UIKit 0x000000018b59a324 <redacted> + 15424
12 UIKit 0x000000018b2f76a0 <redacted> + 1716
13 CoreFoundation 0x0000000186870240 <redacted> + 24
14 CoreFoundation 0x000000018686f4e4 <redacted> + 264
15 CoreFoundation 0x000000018686d594 <redacted> + 712
16 CoreFoundation 0x00000001867992d4 CFRunLoopRunSpecific + 396
17 GraphicsServices 0x000000018ffaf6fc GSEventRunModal + 168
18 UIKit 0x000000018b35efac UIApplicationMain + 1488
19 ObymobiMobileAppiOS 0x0000000100b61f28 wrapper_managed_to_native_UIKit_UIApplication_UIApplicationMain_int_string___intptr_intptr + 344
20 ObymobiMobileAppiOS 0x00000001005387c0 UIKit_UIApplication_Main_string___intptr_intptr + 48
21 ObymobiMobileAppiOS 0x000000010053865c UIKit_UIApplication_Main_string___string_string + 188
22 ObymobiMobileAppiOS 0x000000010009c654 Obymobi_Mobile_App_iOS_Application_Main_string__ + 1508
23 ObymobiMobileAppiOS 0x0000000101007130 wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 160
24 ObymobiMobileAppiOS 0x00000001024fb88c mono_jit_runtime_invoke + 1260
25 ObymobiMobileAppiOS 0x00000001025511e0 mono_runtime_invoke + 128
26 ObymobiMobileAppiOS 0x00000001025553c4 mono_runtime_exec_main + 404
27 ObymobiMobileAppiOS 0x00000001025c6a50 xamarin_main + 1812
28 ObymobiMobileAppiOS 0x00000001024b9688 main + 96
29 libdyld.dylib 0x000000019875aa08 <redacted> + 4
=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries used by your application.
Update
Here is another example of SIGSEGVs I get (this was on simulator) which doesn't have "redacted":-
Any more ideas how to find the problem? Or is it a possible bug in Xamarin?
Native stacktrace:
0 ObymobiMobileAppiOS 0x0011d4f7 mono_handle_native_sigsegv + 311
1 ObymobiMobileAppiOS 0x0014c505 mono_sigsegv_signal_handler + 213
2 libsystem_platform.dylib 0x08c8003b _sigtramp + 43
3 ??? 0xffffffff 0x0 + 4294967295
4 VectorKit 0x10663fe9 -[VKTileProvider tileSource:didFetchTile:forKey:] + 105
5 VectorKit 0x1067140e -[VKTileSource fetchedTile:forKey:] + 62
6 VectorKit 0x106c2617 -[VKTileSetBackedTileSource fetchedTile:forKey:] + 247
7 VectorKit 0x106705b5 -[VKTileSource _fetchedTile:] + 309
8 VectorKit 0x10671985 __49-[VKTileSource decodeData:downloadKey:sourceKey:]_block_invoke_2 + 181
9 libdispatch.dylib 0x08930d8a _dispatch_call_block_and_release + 15
10 libdispatch.dylib 0x0894decf _dispatch_client_callout + 14
11 libdispatch.dylib 0x0893602e _dispatch_queue_drain + 411
12 libdispatch.dylib 0x08935d33 _dispatch_queue_invoke + 197
13 libdispatch.dylib 0x0893820b _dispatch_root_queue_drain + 428
14 libdispatch.dylib 0x089393e7 _dispatch_worker_thread3 + 108
15 libsystem_pthread.dylib 0x08c8d1da _pthread_wqthread + 724
16 libsystem_pthread.dylib 0x08c8ae2e start_wqthread + 30

Answer 1

I came across the same problem. In my case I found some solutions:
If project referenced to wrapper above native library. Check that wrapper and your project have the same architecture - Classic API or Unified API.
1.1 Try to rebuild native project.
1.2 Remove project wrapper from solution and add reference only to output library.
Sometimes, native object are destroyed earlier than .NET. In this case, .NET object have exceptions inside and this error cannot catch with try-catch.
Need to dispose objects correctly.
Try to look crash report inside xcode to get more detailed information.

Answer 2

I faced this problem while using UIDocumentInteractionController. I was using instance of this class as a local parameter and garbage collector was flushing that instance even before the function execution completes. Taking that instance to Global scope solved my problem.

Answer 3

Are the version of Xamarin equal on OS X and Windows? I had similar error. When I updated Xamarin, everything was fine.