iOS Swift画布绘制和边框函数

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建一个画布
        let canvas = UIGraphicsGetCurrentContext()
        
        // 设置画布背景颜色
        canvas?.setFillColor(UIColor.white.cgColor)
        canvas?.fill(CGRect(x: 0, y: 0, width: 200, height: 200))
        
        // 绘制一个矩形
        canvas?.setStrokeColor(UIColor.red.cgColor)
        canvas?.setLineWidth(2.0)
        canvas?.stroke(CGRect(x: 50, y: 50, width: 100, height: 100))
        
        // 添加边框
        let view = UIView(frame: CGRect(x: 50, y: 50, width: 100, height: 100))
        view.layer.borderWidth = 2.0
        view.layer.borderColor = UIColor.blue.cgColor
        
        self.view.addSubview(view)
    }
}