public FirstPageViewModel(INavigationService navigationService, IGeoCoder geoCoder) { Address.Value = "東京都渋谷区"; NextCommand = Address.Select(x => !string.IsNullOrEmpty(x)).ToReactiveCommand(); NextCommand.Subscribe(async _ => { var res = await geoCoder.Forward(Address.Value); if (res != null) { await navigationService.NavigateAsync($"SecondPage?lat={res.Latitude}&lng={res.Longitude}&title={res.DisplayName}"); } }); }