How to fill iPhone X Simulator's background programmatically without Storyboards

Question

So I've created a new iOS single view application with no core data, no test and then I deleted Main.storyboard and the launch screen storyboard. I want to do as much in code as I can so I can understand what I'm doing (since I'm just learning iOS programming). The thing is, that I just cant fill the whole iPhone X screen with a background image. I've tried this first using storyboards and had no problem whatsoever. Am I missing something?

// AppDelegate.swift

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


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

        window = UIWindow(frame: UIScreen.main.bounds)

        let mainController = MainController()

        window?.rootViewController = mainController
        window?.makeKeyAndVisible()

        return true
    }
}


// MainController.swift

import UIKit

class MainController: UIViewController {
    let background: UIImageView = {
        let image = UIImageView(image: #imageLiteral(resourceName: "bg"))
        image.translatesAutoresizingMaskIntoConstraints = false
        return image
    }()
}

extension MainController {
    override func viewDidLoad() {
        super.viewDidLoad()

        setupBackground()
    }
}

extension MainController {
    func setupBackground() {
        view.addSubview(background)

        NSLayoutConstraint.activate([
            background.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            background.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            background.topAnchor.constraint(equalTo: view.topAnchor),
            background.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
    }
}

Answer 1

To summarize the comments above, you need to use a launch storyboard in order for iOS to give you a UIScreen that covers the device's full bounds.

If you don't already have a launch storyboard, create one in Xcode 11 via File > New > File... > Launch Screen . Then make sure to select that launch storyboard under your app target > General > Launch Screen File.