Easiest way to draw a line in swift 3.0

SimpleLine.swift

import UIKit
import XCPlayground
import PlaygroundSupport

public class SimpleLine: UIView  {
    
    public init() {
        super.init(frame: CGRect(x: 0, y: 0, width: 480, height: 320))
        backgroundColor = UIColor.white
    }
    
    public required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    public override func draw(_ rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        context!.setLineWidth(4.0)
        context!.setStrokeColor(UIColor.darkGray.cgColor)
        context!.move(to: CGPoint(x: 100, y: 100))
        context!.addLine(to: CGPoint(x: 300, y: 300))
        context!.strokePath()
    }
    
}

let firstLine = SimpleLine()

PlaygroundPage.current.liveView = firstLine