在Mac上以编程方式添加UIView和UILabel

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建一个UIView
        let myView = UIView(frame: CGRect(x: 100, y: 100, width: 200, height: 200))
        myView.backgroundColor = UIColor.red
        self.view.addSubview(myView)
        
        // 创建一个UILabel
        let myLabel = UILabel(frame: CGRect(x: 50, y: 50, width: 100, height: 50))
        myLabel.text = "Hello World"
        myLabel.textColor = UIColor.white
        myLabel.textAlignment = .center
        myView.addSubview(myLabel)
    }
}