How to create UI programmatically in Xcode 11?

Question

Update: Finally got it working. See below code for SceneDelegate.swift

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let windowScene = (scene as? UIWindowScene) else { return }
        window = UIWindow(frame: windowScene.coordinateSpace.bounds)
        window?.windowScene = windowScene
        window?.rootViewController = ViewController()
        window?.makeKeyAndVisible()
    }

In contrast to the tutorials and the articles online, I was not able to create a working UI with the latest Xcode. This was also the case with Xcode 10, but I did not care at the time.

My steps are as follows:

1. Delete Main.storyboard
2. Delete Main from project settings

Write basic UIWindow code:

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.makeKeyAndVisible()
        let mainVC = ViewController()
        window?.rootViewController = mainVC

        return true
    }

At this point I am getting an error saying cannot find the storyboard named Main in the bundle. If I go ahead and clear the entry from Info.plist, this time it complains that there are not enough characters in the storyboard name.

Any ideas?

Answer 1

These are the steps I followed to get UI working programmatically in Xcode 11.

1) Created a new project as usual

2) I deleted the Main.Storyboard file from the project navigator on the left-hand side.

3) In General tab I removed the Main option from the Main Interface drop-down list 4) Next, go to your Info.plist file and completely remove the Storyboard Name from the list

5) Now if you run the app, it should not crash and it should show you a black screen.

6) Next, go to the SceneDelegate.swift file and initialise your UIWindow object as usual. There is a catch here and is new in Xcode 11. You also set the windowScene property of the window object, or else it won't work.

7) Once that's all done, Go to your ViewController class and set the background colour of the view to some colour and you should be all good.

You can also use templates: Xcode 11 Programmatic UIKit templates

Hope this helped you!!!

Answer 2

This works for me on Xcode 10.3 Swift 5, and Xcode 11 Swift 5.1.

On your new Xcode project, on the Info.plist file, delete the launch screen and main interface file name entries, (don't leave the entry there with an empty string)

Remove the @UIApplicationMain attribute from your AppDelegate class.

Also, this link may help you, you can find info on UIApplicationMain https://docs.swift.org/swift-book/ReferenceManual/Attributes.html

See code below:

//  Created by Juan Miguel Pallares Numa on 9/16/19.
//  Copyright © 2019 Juan Miguel Pallares Numa. All rights reserved.

import UIKit

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var myViewController = ViewController()

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController = myViewController
        window?.makeKeyAndVisible()

        return true
    }
}

import UIKit

class ViewController: UIViewController {

    convenience init() {
        self.init(nibName: nil, bundle: .main)
        view = UIView(frame: UIScreen.main.bounds)
        view.backgroundColor = UIColor(
            displayP3Red: 0.0, green: 0.7, blue: 0.0, alpha: 1.0)
    }
}

// call this file "main.swift"
import Foundation
import UIKit

UIApplicationMain(
    CommandLine.argc, CommandLine.unsafeArgv, nil, NSStringFromClass(AppDelegate.self))