WPF

public partial class App : Application
    {
 protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            MainWindow window = new MainWindow();
            var viewModel = new AllConversationsViewModel();
            MainWindow.DataContext = viewModel;
            window.Show();
        }

private void LoadView(ViewModelBase View)
{
    Type ViewType = View.GetType();

    switch (ViewType.Name.ToLower())
    {
        case "groupviewmodel":
            CurrentView = new GroupViewModel();
            CurrentControl = new crlGroupView();
            break;

        case "ruleviewmodel":
            CurrentView = new RuleViewModel();
            CurrentControl = new crlRuleTree();
            break;
    }

    CurrentControl.DataContext = CurrentView;

    grdMain.Children.Add(CurrentControl);
    Grid.SetRow(CurrentControl, 1);
    Grid.SetColumn(CurrentControl, 0);
    grdMain.Children.Add(CurrentControl);
}