[SOLVED] MonoTouch: RequestReverseGeocode Crashing

I have a simple class which does reverse geocoding, but it causes the app to crash (SIGSEGV), sometimes (50%) but not consistently.

I have tried running it in the UI thread, and in background threads and at different parts of the ViewController's life cycle, but it seems random. Not much is happening in the app when it starts up, mostly just building the UI via MonoTouch.Dialog

    MKReverseGeocoder coder;
    MyMKReverseGeocoderDelegate myMKReverseGeocoderDelegate;
    public void RequestReverseGeocode (CLLocationCoordinate2D coordinate, Action<MKPlacemark> callback)
    {
        myMKReverseGeocoderDelegate= new MyMKReverseGeocoderDelegate (callback); 
        coder = new MKReverseGeocoder (coordinate);
        coder.Delegate = myMKReverseGeocoderDelegate;
        coder.Start ();
    }

    internal class MyCLRequestLocationManagerDelegate : CLLocationManagerDelegate
    {
        Action<CLLocation> callback;

        public MyCLRequestLocationManagerDelegate (Action<CLLocation> callback)
        {
            this.callback = callback;
        }

        public override void UpdatedLocation (CLLocationManager manager, CLLocation newLocation, CLLocation oldLocation)
        {
            manager.StopUpdatingLocation ();
            locationManager = null;
            callback (newLocation);
        }

        public override void Failed (CLLocationManager manager, NSError error)
        {
            callback (null);
        }
    }

The crash details are here:

at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain
(int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
  at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00042] in
/Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:29
  at MonoTouch.UIKit.UIApplication.Main (string[]) [0x00000] in
/Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:34
  at AlternativeFuelingStationLocator.Application.Main (string[]) [0x00000] in
/Users/vink/Dropbox/Dev/iOS/UNIVERSAL/DOE/AlternativeFuelingStationLocator/AlternativeFuelingStationLocator/Main.cs:16
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object
(object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>

Native stacktrace:

   0   AlternativeFuelingStationLocator    0x000e1018
mono_handle_native_sigsegv + 408
    1   AlternativeFuelingStationLocator    0x00011d9f
mono_sigsegv_signal_handler + 351
    2   libsystem_c.dylib                   0x9ad7759b _sigtramp + 43
    3   ???                                 0xffffffff 0x0 + 4294967295
    4   MapKit                              0x01e3b4cf MKMapRectRemainder +
101422
    5   GeoServices                         0x0617f3b8 GEOTileKeyContainsKey +
166198
    6   GMM                                 0x092a3f3d
GEOTileKeyFromGMMTilePath + 31777
    7   ProtocolBuffer                      0x061dfcf1 ProtocolBuffer + 19697
    8   Foundation                          0x0192aa59
___NSURLConnectionDidFinishLoading_block_invoke_0 + 40
    9   Foundation                          0x01928e94
__65-[NSURLConnectionInternal
_withConnectionAndDelegate:onlyActive:]_block_invoke_0 + 40
    10  Foundation                          0x01929eb7
-[NSURLConnectionInternalConnection invokeForDelegate:] + 39
    11  Foundation                          0x01928e4f
-[NSURLConnectionInternal _withConnectionAndDelegate:onlyActive:] + 201
    12  Foundation                          0x01928fd5
-[NSURLConnectionInternal _withActiveConnectionAndDelegate:] + 76
    13  Foundation                          0x0186df6a
_NSURLConnectionDidFinishLoading + 43
    14  CFNetwork                           0x00c68bbd
_ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE
+ 241
    15  CFNetwork                           0x00d355ea
_ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl
+ 584
    16  CFNetwork                           0x00c5f298
_ZN19URLConnectionClient13processEventsEv + 174
    17  CFNetwork                           0x00d3516b
_ZThn52_N25URLConnectionInstanceData24multiplexerClientPerformEv + 21
    18  CFNetwork                           0x00c5f137
_ZN17MultiplexerSource7performEv + 259
    19  CoreFoundation                      0x012ab97f
__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    20  CoreFoundation                      0x0120eb73 __CFRunLoopDoSources0 +
243
    21  CoreFoundation                      0x0120e454 __CFRunLoopRun + 1012
    22  CoreFoundation                      0x0120ddb4 CFRunLoopRunSpecific +
212
    23  CoreFoundation                      0x0120dccb CFRunLoopRunInMode + 123
    24  GraphicsServices                    0x0489f879 GSEventRunModal + 207
    25  GraphicsServices                    0x0489f93e GSEventRun + 114
    26  UIKit                               0x022a6a9b UIApplicationMain + 1175
    27  ???                                 0x0e0b6fcd 0x0 + 235630541
    28  ???                                 0x0e0b6c18 0x0 + 235629592
    29  ???                                 0x0e0b6184 0x0 + 235626884
    30  ???                                 0x0e0b5fdc 0x0 + 235626460
    31  ???                                 0x0e0b612e 0x0 + 235626798
    32  AlternativeFuelingStationLocator    0x00011aef mono_jit_runtime_invoke
+ 1407
    33  AlternativeFuelingStationLocator    0x0022011a mono_runtime_invoke +
170
    34  AlternativeFuelingStationLocator    0x00222e51 mono_runtime_exec_main +
705
    35  AlternativeFuelingStationLocator    0x00222061 mono_runtime_run_main +
929
    36  AlternativeFuelingStationLocator    0x000ad6df mono_jit_exec + 239
    37  AlternativeFuelingStationLocator    0x002f41ca main + 5194
    38  AlternativeFuelingStationLocator    0x00003345 start + 53


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.