Playground demonstrating anchor-based layout constraints

Contents.swift

import PlaygroundSupport
import UIKit

final class LabelViewController: UIViewController {
    var label: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .systemBackground

        label = UILabel()
        label.text = "418 i'm a teapot"
        label.textColor = .placeholderText
        label.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(label)
        NSLayoutConstraint.activate([
            label.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            label.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        ])
    }
}

PlaygroundPage.current.liveView = LabelViewController()