以编程方式设置为根视图控制器时，视图控制器无法正确显示子视图

Question

I've been building my view controllers programmatically by setting a custom view in the loadView() method. While changing my root view controller in AppDelegate to a specified view controller, I've noticed that the view controller does not display it's subviews properly laid out, if it even gets displayed. Using the view debugger, I see that the views are seen as being in the view hierarchy but they are no where to be found, so I end up with blank view controller. What's odd is that when I instead present the view controller from another view controller, only then is it properly laid out and all views are visible. My view controllers all follow the same creation shown below.

class ViewController: UIViewController {


    private var rootView: View? {
        get { return self.viewIfLoaded as? View ?? .none }
        set (view) { self.view = view }
    }


    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


    init() {
        super.init(nibName: nil, bundle: nil)
    }


    override func viewDidLoad() {
        super.viewDidLoad()
    }



    override func loadView() {
        self.rootView = View()
    }

}

And here is how I am creating my custom views for my view controllers

class View: UIView {

    // Lazy declare views here

    fileprivate var shouldSetupConstraints = true


    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupView()
    }


    override func updateConstraints() {
        if(shouldSetupConstraints) {

            // Adding constraints here

            shouldSetupConstraints = false
        }
        super.updateConstraints()
    }


    func setupView() {

        // Adding subviews here 

    }

}

Here is how I am setting the root view controller in my AppDelegate

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    window = UIWindow(frame: UIScreen.main.bounds)
    window?.backgroundColor = Palette.backgroundColor
    window?.rootViewController = MyViewController()
    window?.makeKeyAndVisible()
    return true

}

I expect my programmatically laid out view controllers to be displayed properly while being set as the root view controller, but instead the views are not visible or not laid out properly. They are only displaying correctly when the view controller is presented by another view controller.

Answer 1

Looks like this behavior was being caused by not setting
self.translatesAutoresizingMaskIntoConstraints = false
in setupView() in my custom view.