private void AddRemoveFavoriteButton_Tap(object sender, System.Windows.Input.GestureEventArgs e)
        {
            City     itemViewModel = new City();
            DbEngine EngineWorker  = new DbEngine();

            itemViewModel = CityList.SelectedItem as City;
            string Code = itemViewModel.AirportCode;

            CityList.SelectedItem = null;

            if (EngineWorker.AddAirportToFavorites(Code) == true)
            {
                MessageBox.Show("Το Αεροδρόμιο " + itemViewModel.AirportName + " Προστέθηκε στα Αγαπημένα !"); this.CityList.ItemsSource = GetCity.GetAllCitiesData();
                return;
            }

            else
            {
                MessageBox.Show("Το Aεροδρόμιο " + itemViewModel.AirportName + "Αφαιρέθηκε απο τα Αγαπημένα");
                DbEngine.GetFavoriteAirports();
                List <string> Favorites = new List <string>();
                Favorites = DbEngine.GetFavoriteAirports();
                this.CityList.ItemsSource = null;
                this.CityList.ItemsSource = GetCity.GetFavoriteCities(Favorites);
                if (this.CityList.Items.Count == 0)
                {
                    MessageBox.Show("Δεν βρέθηκε καταχώρηση στα αγαπημένα. Επιστροφή..."); CityList.ItemsSource = GetCity.GetAllCitiesData();
                }
                return;
            }
        }