Swift：以编程方式将自动布局约束从一个视图复制到另一个视图

我有一个UIButton,我在故事板中设置了自动布局约束.我也有一个UIView,我在UIViewController的viewDidLoad方法中启动.我使这个视图(几乎)具有与UIButton相同的所有属性,但是当它在模拟器中运行它时它不会“粘住”到按钮上.这就是我所拥有的：

class ViewController: UIViewController {

    @IBOutlet weak var someButton: UIButton!

    func viewDidLoad() {
        super.viewDidLoad()

        let someView = UIView()
        someView.backgroundColor = UIColor.greenColor()
        someView.frame = someButton.bounds
        someView.frame.origin = someButton.frame.origin
        someView.autoresizingMask = someButton.autoresizingMask
        someView.autoresizesSubviews = true
        someView.layer.cornerRadius = someButton.layer.cornerRadius
        someView.clipsToBounds = true
        someView.userInteractionEnabled = false
        view.insertSubview(someView,belowSubview: someButton)
    }

}

我想我错过了someView.auto布局约束？

编辑：我认为访问UIButton的约束会起作用,但它们似乎是一个空数组.故事板的约束是隐藏的吗？

someView.addConstraints(someButton.constraints)

谢谢.

let someView = UIView()
    someView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(someView)

    view.addConstraints([
        NSLayoutConstraint(item: someView,attribute: .Leading,relatedBy: .Equal,toItem: someButton,multiplier: 1,constant: 0),NSLayoutConstraint(item: someView,attribute: .Trailing,attribute: .Top,attribute: .Bottom,constant: 0)
    ])