public HistoryWeatherPage(WeatherHistoryViewModel vm)
        {
            InitializeComponent();
            ws = new WeatherServices();

            BindingContext = this.viewModel = vm;
        }
        private async void History_Button_Clicked(object sender, EventArgs e)
        {
            if (!clicked && !IsBusy)
            {
                datePicker = new DatePicker
                {
                    Format          = "D",
                    VerticalOptions = LayoutOptions.CenterAndExpand
                };
                datePicker.MaximumDate = DateTime.Now;
                datePicker.MinimumDate = DateTime.Now.AddMonths(-1);

                //datePicker.Format = "dd.MM.yyyy";

                sl.Children.Add(datePicker);
                button_show_history.Text = "SHOW";
                clicked = true;
            }
            else
            {
                WeatherHistoryViewModel whvm = new WeatherHistoryViewModel();
                whvm.City = viewModel.City;

                whvm.Date = new DateTime(datePicker.Date.Year, datePicker.Date.Month, datePicker.Date.Day);
                System.Diagnostics.Debug.WriteLine(".................." + viewModel.City + " " + whvm.Date);
                await Navigation.PushAsync(new HistoryWeatherPage(whvm));
            }
        }
        public HistoryWeatherPage()
        {
            InitializeComponent();
            ws = new WeatherServices();

            viewModel      = new WeatherHistoryViewModel();
            BindingContext = viewModel;
        }