Xcode9学习笔记84

import UIKitclass QuartzView: UIView {    // Only override draw() if you perform custom drawing.    // An empty implementation adversely affects performance during animation.    override func draw(_ rect: CGRect) {        // Drawing code        let context = UIGraphicsGetCurrentContext()                context?.setFillColor(red: 1.0, green: 0.0, blue: 1.0, alpha: 1.0)        context?.fill(rect)        context?.setStrokeColor(red: 0, green: 0, blue: 0, alpha: 1.0)                let rect2 = CGRect(x: 40, y: 80, width: 240, height: 40)        context?.addRect(rect2)        context?.setLineWidth(5.0)        context?.strokePath()                let font = UIFont.boldSystemFont(ofSize: 32)        let text:NSString = "Hello"        let rect3 = CGRect(x: 50, y: 80, width: 80, height: 30)        text.draw(in: rect3, withAttributes: [NSAttributedStringKey.font : font])                context?.setLineWidth(5.0)        context?.setLineCap(CGLineCap.round)        context?.setStrokeColor(red: 1, green: 1, blue: 1, alpha: 1)                let points = [CGPoint(x:40, y:200), CGPoint(x:40, y:300), CGPoint(x:280, y:300), CGPoint(x:40, y:200)]        context?.addLines(between: points)        context?.strokePath()    }}

    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view, typically from a nib.                let rect = self.view.bounds//获得当前根视图的显示区域        let view = QuartzView()        view.frame = rect                self.view.addSubview(view)    }