Mastering Xamarin.Forms - Second Edition

Updating MainViewModel

In order to move the navigation functionality from MainPage to MainViewModel, we will need to add two new Command properties—one for creating a new log entry and another for viewing the details of an existing log entry:

      public class MainViewModel : BaseViewModel      {          // ...          Command<TripLogEntry> _viewCommand;          public Command<TripLogEntry> ViewCommand           {              get               {                    return _viewCommand                      ?? (_viewCommand = new Command<TripLogEntry>(async (entry) => await ExecuteViewCommand(entry)));               }          }          Command _newCommand;          public Command NewCommand           {              get               {                  return _newCommand                      ?? (_newCommand = new Command(async () => await ExecuteNewCommand()));               }           }          async Task ExecuteViewCommand(TripLogEntry entry)          { await NavService.NavigateTo<DetailViewModel, ...