Polinominal.swift

/// Polynomial.swift

import Cocoa

fileprivate let HOPS = 100
fileprivate RANDFLOAT: () -> CGFloat = { 
    return CGFloat(arc4random % 128) % 128.0
}
fileprivate let funcRect = CGRect(x: -20, y: -20, width: 40, height: 40)

class Polynomial: NSObject {
    var terms = [CGFloat]()
    var termCount: Int = 0
    var color: CGColor?


    override init() {
        super.init()

        color = CGColor(red: RANDFLOAT(), green: RANDFLOAT(), blue: RANDFLOAT(), alpha: 0.5)
        // CFMakeCollectiable()은 없어졌다...
        termCount = Int(arc4random()) % 3 + 2
        terms = (0..<termCount).map{ _ in 
            return 5.0 - CGFloat(arc4random() % 100) / 10.0
        }
    }

    func value(at x: CGFloat) -> CGFloat {
        return terms.reduce(0, {$0 * x + $1 })
    }


    func draw(in rect: CGRect, context ctx: CGContext) { 
        ctx.saveGstate()
        let tf = CGAffineTransform(a: rect.width / funcRect.width,
                                b: 0,
                                c: 0,
                                d: rect.height / funcRect.height,
                                tx: rect.width / 2,
                                ty: rect.height / 2)
        ctx.concatenate(tf)
        ctx.setStrokeColor(color)
        ctx.setLineWidth(0.4)

        let distance = funcRect.width / HOPS
        var currentX = funcRect.minX
        var first = true;
        while currentX <= funcRect.maxX {
            let currentY = value(at: currentX)
            if first {
                ctx.move(CGPoint(x: currentX, y: currentY))
                first = false
            } else {
                addLine(to: CGPoint(x: currentX, y: currentY))
            }
            currentX += distance
        }
        ctx.strokePath()
        ctx.restoreGState()
    }

    // finalize는 deprecated됨.
}

polynominalView.swift

/// PolynomialView.swift

import Cocoa

class PolynomialView: NSView {
    var polynomials = [Polynomial]()

    @IBAction func createNewPolynomial(_ sender: Any) {
        let p = Polynomial()
        polynomials.append(p)
        setNeedsDisplay(bounds)
    }

    @IBAction func deleteRandomPolynomial(_ sender: Any) {
        guard !polynomials.isEmpty else { return }
        let i = Int(arc4random()) % polynomials.count
        polynomials.remove(at: i)
        setNeedsDisplay(bounds)
    }

    override func draw(_ rect: CGRect) {
        NSColor.whiteColor.set()
        NSBezierPath.fill(bounds)
        if let ctx = NSGraphicsContext.current() {
            polynomials.forEach{  $0.draw(in: self.bounds, context: ctx) }
        }
    }
}