Swift 3 Playgroundで曲線波形を描画する

Xcode 8.2を使用

import UIKit
import PlaygroundSupport

// ベースとなるUIViewを作成
var dim: CGFloat = 500
let container = UIView(frame: CGRect(x: 0, y: 0, width: dim, height: dim))
PlaygroundPage.current.needsIndefiniteExecution = true
PlaygroundPage.current.liveView = container

// 曲線を描画するためのUIViewサブクラス
class MyView: UIView {
    override func draw(_ rect: CGRect) {
        super.draw(rect)

        let path = UIBezierPath()
        path.move(to: CGPoint(x: 0, y: 200))

        let span: CGFloat = 20
        var pos1 = path.currentPoint

        for idx in 1...25 {
            let plotX: CGFloat = span * CGFloat(idx)
            let plotY: CGFloat = (idx % 2 == 0) ? 200 : 300
            let pos = CGPoint(x: plotX, y: plotY)
            // 曲線の追加と調整
            var pos2 = pos
            pos1.x += span * 0.5
            pos2.x -= span * 0.5
            path.addCurve(to: pos, controlPoint1: pos1, controlPoint2: pos2)
            pos1 = pos
        }

        path.lineWidth = 4.0
        UIColor.white.setStroke()
        path.stroke()
    }
}

let view = MyView(frame: container.bounds)
view.backgroundColor = UIColor.red
container.addSubview(view)