如何在iOS中的ViewController中添加View以下的其他视图？

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let customView = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
        customView.backgroundColor = .blue
        customView.center = view.center
        
        let label = UILabel(frame: CGRect(x: 0, y: 0, width: 100, height: 50))
        label.center = customView.center
        label.text = "Hello, World!"
        label.textColor = .white
        label.textAlignment = .center
        
        customView.addSubview(label)
        view.addSubview(customView)
    }
}