Sample AppDelegate that starts the application without using storyboards

AppDelegate.swift

//
//  AppDelegate.swift
//  MediumSamples
//
//  Created by Fernando Ortiz on 1/3/17.
//  Copyright © 2017 Fernando Martín Ortiz. All rights reserved.
//

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)
        
        let attribute = "Sample"
        let initialViewController = SampleViewController(veryImportantAttribute: attribute)
        
        window!.rootViewController = initialViewController
        window!.makeKeyAndVisible()
        
        return true
    }
}