iOS Webrtc - Crash in RTCPeerConnectionFactory.VideoSourceWithCapturer - ios

Question

I am using static library "libWebRTC.a" to create IOS App by binding it using Xamarin binding.
when I call _factory.VideoSourceWithCapturer(capturer, mediaConstraints); in this code the application crashes
RTCVideoTrack CreateLocalVideoTrack()
{
RTCVideoTrack localVideoTrack = null;
AVCaptureDevice.RequestAccessForMediaType(AVMediaType.Video, (bool isAccessGranted) =>
{
if (isAccessGranted)
{
String cameraID = "";
for (int i = 0; i < AVCaptureDevice.DevicesWithMediaType(AVMediaType.Video).Length; i++)
{
if (AVCaptureDevice.DevicesWithMediaType(AVMediaType.Video)[i].Position == AVCaptureDevicePosition.Front)
{
cameraID = AVCaptureDevice.DevicesWithMediaType(AVMediaType.Video)[i].LocalizedName;
break;
}
}
//do something
RTCVideoCapturer capturer = RTCVideoCapturer.CapturerWithDeviceName(cameraID);
RTCMediaConstraints mediaConstraints = DefaultMediaStreamConstraints();
RTCVideoSource videoSource = _factory.VideoSourceWithCapturer(capturer, mediaConstraints);
localVideoTrack = _factory.VideoTrackWithID(#"ARDAMSv0", videoSource);
}
else
{
}
});
return localVideoTrack;
}
and this is the message :
Native stacktrace:
critical: 0 libmonosgen-2.0.dylib 0x0000000100a18184 mono_handle_native_sigsegv + 260
critical: 1 libmonosgen-2.0.dylib 0x0000000100a23618 mono_sigsegv_signal_handler + 220
critical: 2 libsystem_platform.dylib 0x0000000185a08348 _sigtramp + 52
critical: 3 TestRTC 0x000000010020b1fc _ZN7cricket13VideoCapturer15SetCaptureStateENS_12CaptureStateE + 52
critical: 4 TestRTC 0x0000000100214764 _ZN7cricket19WebRtcVideoCapturer5StartERKNS_11VideoFormatE + 1084
critical: 5 TestRTC 0x000000010020b190 _ZN7cricket13VideoCapturer14StartCapturingERKNS_11VideoFormatE + 52
critical: 6 TestRTC 0x0000000100202020 _ZN7cricket14CaptureManager26StartWithBestCaptureFormatEPNS_18VideoCapturerStateEPNS_13Vi
deoCapturerE + 204
critical: 7 TestRTC 0x0000000100201ea0 _ZN7cricket14CaptureManager17StartVideoCaptureEPNS_13VideoCapturerERKNS_11VideoFormatE + 196
critical: 8 TestRTC 0x000000010028c658 _ZN3rtc21FunctorMessageHandlerIbNS_14MethodFunctor2IN7cricket14CaptureManagerEMS3_FbPNS2_13VideoCapturerERKNS2_11VideoFormatEEbS5_S8_EEE9OnMessageEPNS_7MessageE + 24
critical: 9 TestRTC 0x00000001001f10c4 ZN3rtc6Thread22ReceiveSendsFromThreadEPKS0 + 116
critical: 10 TestRTC 0x00000001001dc338 _ZN3rtc12MessageQueue3GetEPNS_7MessageEib + 156
critical: 11 TestRTC 0x00000001001f0df0 _ZN3rtc6Thread15ProcessMessagesEi + 108
TestRTC[634:2