入门挑战-超简单的UI代码在Xamarin.ios中不起作用

Question

我正在尝试通过Xamarin.ios中的代码构建用户界面。该代码运行时没有错误消息，但屏幕只是纯白色的表面。

我尝试将以下代码添加到ViewDidLoad中，并且能够逐行逐步调试该代码，但是没有呈现任何内容。遗失了什么？

    public override void ViewDidLoad()
    {            
        base.ViewDidLoad();

        UIButton button = new UIButton(UIButtonType.RoundedRect);
        button.SetTitle("Hello", UIControlState.Normal);
        button.Frame = new CGRect(50, 50, 50, 50);
        this.View.AddSubview(button);

        View.BackgroundColor = UIColor.Blue;
        this.Title = "Scroll view";

        view1 = new UIView(new CGRect(100,100,100,100));
        view1.BackgroundColor = UIColor.Blue;
        View.AddSubview(view1);

        var label1 = new UILabel(new CGRect(10, 60, 300, 30));
        label1.Text = "Funkar";
        label1.BackgroundColor = UIColor.Gray;
        view1.Add(label1);

        scrollView = new UIScrollView(new CGRect(200, 200, 200, 200));
        scrollView.BackgroundColor = UIColor.Red;
        View.AddSubview(scrollView);

FinishedLaunching看起来像这样：

    public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
    {
        Window = new UIWindow(UIScreen.MainScreen.Bounds);

        viewController = new MyViewController();

        navigationController = new UINavigationController();
        navigationController.PushViewController(viewController, false);

        Window.RootViewController = navigationController;
        Window.MakeKeyAndVisible();

        return true;
    }