public MainPage()
{
this.InitializeComponent();
DataContext = viewModel = new ContactsViewModel();
this.Loaded += MainPage_Loaded;
AuthenticationHelper.PlatformParameters = new PlatformParameters(PromptBehavior.Auto, false);
}
public ContactsSource(ContactsViewModel viewModel, ContactsViewController controller)
{
this.viewModel = viewModel;
this.controller = controller;
}