Core Graphics experiment: draw a star

Star.swift

//: Playground - noun: a place where people can play

import UIKit
import PlaygroundSupport

internal final class StarView: UIView {
    let numberOfEdges = 5
    let fillColor: UIColor = .red
    let strokeColor: UIColor = .black
    let lineWidth: CGFloat = 2
    let innerRadiusRatio: CGFloat = 0.5
    let outerRadius:  CGFloat = 50
    
    override func draw(_ rect: CGRect) {
        
        guard let context = UIGraphicsGetCurrentContext() else { return }
        //Draw your stuff in here...
        
        let origin = CGPoint(x: rect.width / 2, y: rect.height / 2)
        let angle = 360 / numberOfEdges
        let lines = (0..<numberOfEdges * 2).map { (index) -> CGPoint in
            var point = origin
            let radius = index % 2 == 0 ? outerRadius : (outerRadius * innerRadiusRatio)
            let pointRotation = index % 2 == 0 ? CGFloat(angle * index) : CGFloat(angle * index) + CGFloat(angle / 2)
            
            point.y -= radius
            point = point.rotate(around: origin, with: pointRotation)
            
            return point
        }
        context.addLines(between: lines)
        context.setStrokeColor(strokeColor.cgColor)
        context.setFillColor(fillColor.cgColor)
        context.setLineWidth(lineWidth)
        context.fillPath()
        
    }
}

extension CGPoint {
    func rotate(around center: CGPoint, with degrees: CGFloat) -> CGPoint {
        let dx = self.x - center.x
        let dy = self.y - center.y
        let radius = sqrt(dx * dx + dy * dy)
        let azimuth = atan2(dy, dx) // in radians
        let newAzimuth = azimuth + degrees * CGFloat(M_PI / 180.0) // convert it to radians
        let x = center.x + radius * cos(newAzimuth)
        let y = center.y + radius * sin(newAzimuth)
        return CGPoint(x: x, y: y)
    }
}

let view = StarView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
view.backgroundColor = .white
PlaygroundPage.current.needsIndefiniteExecution = false
PlaygroundPage.current.liveView = view