How can I make the border color of a UIView gradient? 

I have declared a UIView from my storyboard and I know how to make the border color solid. But I can't find out how to make the border gradient. 

```
 @IBOutlet weak var view: UIView! 

override func awakeFromNib() {
        super.awakeFromNib() 

    let gradient = CAGradientLayer()

    gradient.colors = [UIColor.white.cgColor, UIColor.black.cgColor]

        view.backgroundColor = nil
        view.layer.cornerRadius = view.bounds.width / 2
        view.layer.borderWidth = 3
        view.layer.borderColor = colorOutline.cgColor

        nah.textColor = colorCircleBlue

    }

```