วิธีใช้คำสั่งหยุดการทำงาน และการเก็บค่าใน Class ของ Xamarin Form

exit(0); 

    // Function called from OnDestroy
    protected void saveset(){

        //store
        var prefs = Application.Context.GetSharedPreferences("MyApp", FileCreationMode.Private);
        var prefEditor = prefs.Edit();
        prefEditor.PutString("PrefName", "Some value");
        prefEditor.Commit();

    }

    // Function called from OnCreate
    protected void retrieveset()
    {
        //retreive 
        var prefs = Application.Context.GetSharedPreferences("MyApp", FileCreationMode.Private);              
        var somePref = prefs.GetString("PrefName", null);

        //Show a toast
        RunOnUiThread(() => Toast.MakeText(this, somePref, ToastLength.Long).Show());

    }