How to save video when recording is interrupted by sending the application to background on windows phone 8 - windows-phone-8

Question

I am expermenting with video recording on Windows Phone 8. I want to handle the situation when user is putting my app to background, while it is recording a video. I would like to save the already recorded video before quitting.
I am handling this situation using the code from this example:
https://msdn.microsoft.com/en-us/library/windows/apps/mt243896.aspx
private async Task StopRecordingAsync()
{
try
{
Debug.WriteLine("Stopping recording...");
_isRecording = false;
await _mediaCapture.StopRecordAsync();
Debug.WriteLine("Stopped recording!");
}
catch (Exception ex)
{
Debug.WriteLine("Exception when stopping video recording: {0}", ex.ToString());
}
}
I am calling this method from the:
protected async override void OnNavigatingFrom(NavigatingCancelEventArgs e)
But the video is not being saved. In the debug console I get only the first message: "Stopping recording...", but there is no "Stopped recording!" message logged. It seems like the resources are being destroyed before I can handle them.

Answer 1

When your app is moved to the background you only have a short amount of time to run code.
Instead of having saving be triggered when you navigate from the page, instead look at the Application.Suspending event which allows you to use a deferral to try and run your code for a bit longer so you can finish tidying up before your app loses it's resource allocation.
Something like:
async protected void OnSuspending(object sender, SuspendingEventArgs args)
{
SuspendingDeferral deferral = args.SuspendingOperation.GetDeferral();
await StopRecordingAsync();
deferral.Complete();
}