Creating and implementing the TwitterSignInPageViewModel using C#

In this section, we'll take a look at how to create the TwitterSignInPageViewModel class so that it can communicate with our TwitterSignInPage, as well as any data bindings associated with the ContentPage that will be used by the ViewModel. We will create and implement the underlying C# code for our ViewModel, which will be used by our TwitterSignInPage code-behind file so that it can navigate within our NavigationStack.

Let's start by creating the TwitterSignInPageViewModel for our TrackMyWalks app by performing the following steps:

1. Ensure that the TrackMyWalks solution is open within the Visual Studio for Mac IDE.
2. Next, right-click on the ViewModels folder, and choose Add | New File... from the pop-up menu, as you did in the section entitled Creating the WalksMainPageViewModel using C# within Chapter 5, MVVM and Data Binding.
3. Then, ensure that the TwitterSignInPageViewModel.cs file, which is located within the ViewModels folder...