import UIKit

@main
final class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil
    ) -> Bool {
        let label = UILabel()
        label.text = "Hello, world!"
        label.font = .systemFont(ofSize: 32, weight: .bold)
        label.textAlignment = .center

        let viewController = UIViewController()
        viewController.view.backgroundColor = .systemBackground
        viewController.view.addSubview(label)
        label.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            label.centerXAnchor.constraint(equalTo: viewController.view.centerXAnchor),
            label.centerYAnchor.constraint(equalTo: viewController.view.centerYAnchor),
        ])

        let window = UIWindow(frame: UIScreen.main.bounds)
        window.rootViewController = viewController
        window.makeKeyAndVisible()
        self.window = window
        return true
    }
}