TrailingNegativeConstraint.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white

        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.text = "Hello World!"
        label.textColor = .black
        label.backgroundColor = .red
        
        view.addSubview(label)
        NSLayoutConstraint.activate([
            label.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            label.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 30),
            view.trailingAnchor.constraint(equalTo: label.trailingAnchor, constant: 30)
        ])
        self.view = view
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()