Weekend Playground fun: TreeView

TreeView.swift

import UIKit

typealias Bough = (rotation:CGFloat, length: CGFloat, scale: CGFloat, hue: CGFloat)

final class TreeView : UIView {
    private let limit = 10
    
    private let boughs : [Bough] = [
        (rotation:  -25, length: 85,  scale: 0.75, hue: 0.04),
        (rotation:   30, length: 100, scale: 0.65, hue: 0.02)
    ]
    
    override func draw(_ rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()!
        context.setLineCap(.round)
        context.setLineWidth(24)
        context.translateBy(x: self.center.x, y: self.frame.size.height - 25)
        context.move(to: CGPoint.zero)
        context.rotate(by: CGFloat.pi )
        branch( context: context, hue: 0.05, depth: 0 )
    }
    
    func branch( context: CGContext, hue: CGFloat, depth: Int ) {
        guard depth < limit else { return }
        
        for bough in boughs {
            context.saveGState(); defer { context.restoreGState() }
            let point = CGPoint(x:0,y:bough.length)
            context.rotate(by: bough.rotation * CGFloat.pi / 180 )
            context.setStrokeColor( UIColor(hue: hue, saturation: 0.8, brightness: 0.6, alpha: 1.0 ).cgColor )
            context.move(to: CGPoint.zero)
            context.addLine(to: point)
            context.strokePath()
            context.translateBy(x: 0, y: bough.length)
            context.scaleBy(x: bough.scale, y: bough.scale)
            self.branch(context: context, hue: (hue + bough.hue), depth: depth + 1)
        }
    }
}

let view = TreeView(frame: CGRect(x: 0, y: 0, width: 512, height: 384))