如何绘制一个只是一个圈子的自定义UIView - iPhone应用程序

import UIKit

class CircleView: UIView {

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        // 创建一个圆形路径
        let circlePath = UIBezierPath(ovalIn: rect)

        // 设置填充颜色
        UIColor.blue.setFill()

        // 绘制圆形
        circlePath.fill()
    }
}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // 创建一个新的CircleView实例
        let circleView = CircleView(frame: CGRect(x: 50, y: 100, width: 100, height: 100))

        // 将CircleView添加到视图层次结构中
        view.addSubview(circleView)
    }
}