Material design introduced a new lightweight way to provide feedback to a user, something that sits between the AlertDialog and Toast alternatiives with a funny name: SnackBar.
A Snackbar appears at the bottom of the view and can optionally display an additional custom button.

Here are the basic steps to show a SnackBar:

-Open Visual Studio and create a new blank Android app

-Using Nuget add the Xamarin.Android.Support.Design library, this will let you target Android releases older than v21

• -Using the code generated by the template, lets make the SnackBar appear when the default button is pressed.

-Add this code inside MainActivity’s OnCreate method

protected override void OnCreate(Bundle bundle)
{
    base.OnCreate(bundle);

    // Set our view from the "main" layout resource
    SetContentView(Resource.Layout.Main);

    // Get our button from the layout resource,
    // and attach an event to it
    Button button = FindViewById<Button>(Resource.Id.MyButton);

    button.Click += (s, e) =>
        {
            //Creates the Snackbar 
            Snackbar snackBar = Snackbar.Make(button, "Text", Snackbar.LengthIndefinite);
            //Show the snackbar
            snackBar.Show();
        };
    }
}

• -Compile the project and wait until build succeeds, be patient if operation takes more than than usual since this delay is due to the fact that the missing packages are downloading and their size is quite huge. If you stop compilation download will fail and you’ll start having a lot of “…invalid zip” error. in this case delete the zip folder mentioned on error message and try again.
• -You’ll now see this error message:
• 
• -Let’s fix it adding the required theme (you can create your own deriving from Theme.AppCompat of course)

  [Activity(Label = "TestSnackBar2", MainLauncher = true, Icon = "@drawable/icon", Theme = "@style/Theme.AppCompat")]

• -Run the project again and you’ll see this bar appear at the bottom of the view
• 
• -Quite sad indeed, luckily the SnackBar can be customized, so let’s add more code:

button.Click += (s, e) =>
            {
                //Creates the Snackbar and subscribes the button press event
                Snackbar snackBar = Snackbar.Make(button, "Text", Snackbar.LengthIndefinite).SetAction("Ok", (v) =>
                {
                    Console.WriteLine("Done");
                });

                //set  action button text color 
                snackBar.SetActionTextColor(Android.Graphics.Color.Green);

                //Set action button text size
                TextView txtAction = snackBar.View.FindViewById<TextView>(Resource.Id.snackbar_action);
                txtAction.SetTextSize(Android.Util.ComplexUnitType.Dip, 18);

                //Set message text size and color
                TextView txtMessage = snackBar.View.FindViewById<TextView>(Resource.Id.snackbar_text);
                txtMessage.SetTextColor(Android.Graphics.Color.Red);
                txtMessage.SetTextSize(Android.Util.ComplexUnitType.Dip, 12);

                //Show the snackbar
                snackBar.Show();
            };

• -And there you go, a custom SnackBar
• 

If you’re wondering why you need to pass a reference to a view (Button in our case) as SnackBar first parameter is because internally it walks up the visual tree so that can properly position itself at bottom position.