How do I draw a cosine or sine curve in Swift?

Question

I\'ve been trying to figure out how to use UIBezierPath for this project, but I don\'t know how to implement this kind of drawing. I can draw a circle and arcs and straight

Answer 1

This allows you to place a sine wave inside a rect:

    func generateWave(cycles: Int, inRect: CGRect, startAngleInDegrees: CGFloat = 0) -> UIBezierPath {
        let dx = inRect.size.width
        let amplitude = inRect.size.height
        let scaleXToDegrees = 1 / (inRect.size.width / 360.0 / CGFloat(cycles))
        let path = UIBezierPath()
        for x in stride(from: 0, to: dx + 5, by: 5) {
            let y = sin(D2R(startAngleInDegrees + x * scaleXToDegrees)) * amplitude / 2
            let p = CGPoint(x: x + inRect.origin.x, y: y + inRect.origin.y)
            if x == 0 {
                path.move(to: p)
            } else {
                path.addLine(to: p)
            }
        }
        return path
    }

To animate:

    override func update(_ currentTime: TimeInterval) {
        shape?.removeFromParent()

        let path = generateWave(cycles: 7, inRect: targetRect, startAngleInDegrees: currentStartAngle)
        shape = SKShapeNode(path: path.cgPath)
        shape!.strokeColor = .red
        shape!.lineWidth = 1
        self.addChild(shape!)
        currentStartAngle += 5
    }