Today I Learned How to Handle Local Notifications in Xamarin on Android

In my previous example I detailed how to schedule notifications in Xamarin on Android but didn’t show the Xamarin Forms application reacting to that specific notification.  Let’s fix that.

First override the OnNewIntent method in the MainActivity.  We override this method so notifications will work if the application is currently running or is stopped and the notification started the application.  In the OnNewIntent method you put code that makes sure it’s a notification you want to respond to then extracts any needed information from the notification.  An example is below:

protected override void OnNewIntent(Intent intent)
{
  // Let the parent do it's thing.
  base.OnNewIntent(intent);

  // Is this a notification intent? The action should look like:
  //
  // <packagename>.NOTIFICATION-<ID>
  //
  var expectedActionName = BuildActionName("");
  if (intent.Action == null || !intent.Action.StartsWith(expectedActionName))
  {
    // Not a notification intent. Do nothing.
    return;
  }

  // Extract the notification information.
  var extractedNotification = new Notification
  {
    Id = intent.Action.Substring(intent.Action.IndexOf("-", StringComparison.Ordinal) + 1), // The ID is part of the action. 
    Title = intent.GetStringExtra(TitleExtrasKey), // These fields are extras but should exist.
    Message = intent.GetStringExtra(MessageExtrasKey) // These fields are extras but should exist.
  };

  // Do whatever you want with the notification.
  NotificationRecieved(extractedNotification);
}

The first thing the method does is check if it’s a notification we are interested in.  In this example we know that notifications we are interested in have a certain action name so we check for that.

var expectedActionName = BuildActionName("");
if (intent.Action == null || !intent.Action.StartsWith(expectedActionName))
{
  // Not a notification intent. Do nothing.
  return;
}

Next we extract the notification information.  In this case we only pull out the ID, title, and message but you could add other things as needed.

var extractedNotification = new Notification
{
 Id = intent.Action.Substring(intent.Action.IndexOf("-", StringComparison.Ordinal) + 1), // The ID is part of the action. 
 Title = intent.GetStringExtra(TitleExtrasKey), // These fields are extras but should exist.
 Message = intent.GetStringExtra(MessageExtrasKey) // These fields are extras but should exist.
};

Finally do whatever you want with this the notification.  This could be showing a certain screen in your application, updating some data, etc.  In this example we just call a handling method and leave it up to your very vivid imagination.

If you want a working example checkout the XPlugins.Notifications plugin.  If you are writing an Xamarin Forms application you can use the plugin to handle notifications in both Android and iOS.

P.S. – Another post about communication and another music video about communication.  The song is not about communication but the video is.  Just watch it and you will figure it out.

P.P.S. – This is the only song I can play on guitar and sing at the same time.  Both poorly.