xcode给一张矩形图片添加圆角效果swift代码

import UIKit

import Foundation

class ViewController: UIViewController {

    

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

        let image = UIImage(named: "timg")

        let imageView = UIImageView (image:image)

        let rect = CGRect(x: 20, y: 20, width: 400, height: 400)

        imageView.frame = rect

        imageView.layer.cornerRadius = 100

        imageView.layer.masksToBounds = true

        

        self.view.addSubview(imageView)

        

    }

    

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

    

    

}