iOS Swift. How to create app without storyboard

There is a question: Is it possible to create iOS application . without using Storyboard?. Answer is Yes, it is possible. For implementing this we must create our custom UIWindow and set root controller for it. In code below I show how to do this.

AppDelegate class and didFinishLaunchingWithOptions method

In AppDelegate class method didFinishLaunchingWithOptions we create UIWindow and set root controller for it.

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, 
        didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        
        self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window?.makeKeyAndVisible()
        
        let viewController = ViewController()
        let navigationController = UINavigationController(rootViewController: viewController)
        self.window?.rootViewController = navigationController
        
        return true
    }
}

ViewController

Our ViewController. We set title and add button to center of it using constraints.

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.title = "No Storyboard"
        self.view.backgroundColor = UIColor.white
        
        let button =  UIButton(type: .system)
        button.setTitle("Success", for: .normal)
        self.view.addSubview(button)
        
        button.translatesAutoresizingMaskIntoConstraints = false
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.widthAnchor.constraint(equalToConstant: 200).isActive = true
        button.heightAnchor.constraint(equalToConstant: 50).isActive = true
    }
}

Result