MonoTouch SIGSEGV crash using navigationcontroller

In the MonoTouch simulator I am getting random crashes with the following diagnostic:

/tmp/mono-gdb-commands.FV1b8V:1: Error in sourced command file:
unable to debug self

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.

The trace mentions "UISearchDisplayController dealloc" :

  at (wrapper managed-to-native) MonoTouch.ObjCRuntime.Messaging.void_objc_msgSend (intptr,intptr) <IL 0x00024, 0xffffffff>
  at MonoTouch.Foundation.NSObject/MonoTouch_Disposer.Drain (MonoTouch.Foundation.NSObject) [0x0002a] in /Users/plasma/Source/iphone/monotouch/Foundation/NSObject.cs:305
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void__this___object (object,intptr,intptr,intptr) <IL 0x00052, 0xffffffff>
  at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
  at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00038] in /Users/plasma/Source/iphone/monotouch/UIKit/UIApplication.cs:26
  at TestCase.Application.Main (string[]) [0x00000] in /Users/user/Projects/Junk 2/StarTrack/Main.cs:13
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>

   Native stacktrace:

0   TestCase                            0x000d1965 mono_handle_native_sigsegv + 343
1   TestCase                            0x0000ffb4 mono_sigsegv_signal_handler + 322
2   libSystem.B.dylib                   0x91b3745b _sigtramp + 43
3   ???                                 0xffffffff 0x0 + 4294967295
4   UIKit                               0x01f7ab5a **-[UISearchDisplayController dealloc]** + 106
5   ???                                 0x0aa9a194 0x0 + 178889108
6   ???                                 0x0fcea9c4 0x0 + 265202116
7   ???                                 0x077520d6 0x0 + 125116630
8   TestCase                            0x0000fd6f mono_jit_runtime_invoke + 1332
9   TestCase                            0x001ee239 mono_runtime_invoke + 137
10  TestCase                            0x0029e9ab monotouch_trampoline + 2527
11  Foundation                          0x0140e94e __NSThreadPerformPerform + 251
12  CoreFoundation                      0x00ea08ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
13  CoreFoundation                      0x00dfe88b __CFRunLoopDoSources0 + 571
14  CoreFoundation                      0x00dfdd86 __CFRunLoopRun + 470
15  CoreFoundation                      0x00dfd840 CFRunLoopRunSpecific + 208
16  CoreFoundation                      0x00dfd761 CFRunLoopRunInMode + 97
17  GraphicsServices                    0x0404c1c4 GSEventRunModal + 217
18  GraphicsServices                    0x0404c289 GSEventRun + 115
19  UIKit                               0x01ce0c93 UIApplicationMain + 1160
20  ???                                 0x09d54933 0x0 + 164972851
21  ???                                 0x09d53384 0x0 + 164967300
22  ???                                 0x09d530be 0x0 + 164966590
23  ???                                 0x09d53216 0x0 + 164966934
24  TestCase                            0x0000fd6f mono_jit_runtime_invoke + 1332
25  TestCase                            0x001ee239 mono_runtime_invoke + 137
26  TestCase                            0x001f0920 mono_runtime_exec_main + 669
27  TestCase                            0x001efd0a mono_runtime_run_main + 843
28  TestCase                            0x000a3c62 mono_jit_exec + 200
29  TestCase                            0x002a25eb main + 3838
30  TestCase                            0x000030c9 _start + 208
31  TestCase                            0x00002ff8 start + 40
32  ???                                 0x00000002 0x0 + 2

Have cut down the app to the absolute minimum necessary to reproduce the crash, and hunted for possible references to descoped and garbage-collected variables. There are no XIBs: it is code-only.

A navigation controller has a tableview for despatch; tapping on a table row takes you to a table of 22,000 rows with a searchbar. The user types into the searchbar, taps on a filtered table row, and is immediately popped back to the first tableview. This can be done from two to twenty times before crashing. (The crash occurs immediately upon tapping a table row in the first tableview). Apart from the crashes, the app works exactly as expected.

Any ideas or suggestions would be -so- much appreciated, am at wits end after days of effort. Btw I proposed using MonoTouch after the infamous takeover and this is our first app.

The classes listed below would seem to be the most relevant; these classes and others are here: http://www.whaleandseal.org/Test/Crash.pdf and a self-contained test case is at http://www.whaleandseal.org/Test/TestCase.zip .

AppDelegate
        TTNavController

TTNavigationController
        despatchTable

TTTableDelegate
        new FromTableController(…)

FromTableController
        searchBar
        searchController

FromSearchResultsSource

FromSearchResultsDelegate

Adding this in your FromTableController seems to fix the problem:

protected override void Dispose (bool disposing)
{
    searchController.SearchResultsSource = null;
    searchController.Delegate = null;
    base.Dispose (disposing);
}

Solution was inspired by this: How can UISearchDisplayController autorelease cause crash in a different view controller?