我如何为我的按钮创建一个约束，这样它就不会弄乱它的大小

override func viewDidLoad() {
    super.viewDidLoad()
    
    let button = UIButton()
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setTitle("按钮", for: .normal)
    button.backgroundColor = .blue
    view.addSubview(button)
    
    let leadingConstraint = NSLayoutConstraint(item: button, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1.0, constant: 20.0)
    let topConstraint = NSLayoutConstraint(item: button, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: 20.0)
    
    view.addConstraints([leadingConstraint, topConstraint])
}