spinner.txt

       <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner1" />
//Define Spinner
Spinner spinner = FindViewById<Spinner>(Resource.Id.spinner1);
// dfeine data set
List<string> scaleNames = new List<string>();
scaleNames.Add("Developer");
            scaleNames.Add("Admins");
            scaleNames.Add("Desginner");
            //asgin dataset
            var scaleAdapter = new ArrayAdapter<string>(
                this, Android.Resource.Layout.SimpleSpinnerItem, scaleNames);

scaleAdapter.SetDropDownViewResource
                (Android.Resource.Layout.SimpleSpinnerDropDownItem);

            spinner.Adapter = scaleAdapter;
            // button click evnet
            spinner.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(spinner_ItemSelected);

 
        //spinner click
        private void spinner_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)
{
    Spinner spinner = (Spinner)sender;

    string toast = string.Format("The planet is {0}", spinner.GetItemAtPosition(e.Position));
    Toast.MakeText(this, toast, ToastLength.Long).Show();
}