Swift MacOS label Gradient Text

I have a label in a MacOS project which when connected becomes an NSTextfield. I want to make the text have a gradient overlay.

I have some code to do this with an IOS UIButton, but for this project I keep getting the error that NSView has no such thing called mask and I don't know what to mask it to

extension NSTextField {
func applyGradientText(colors: [CGColor]) {
    let gradient = CAGradientLayer()
    gradient.frame = bounds
    gradient.startPoint = CGPoint(x: 0.0, y: 0.5)
    gradient.endPoint = CGPoint(x: 1.0, y: 0.5)
    gradient.colors = colors
    layer?.insertSublayer(gradient, at: 0)
    let overlayView = NSView(frame: bounds)
    overlayView.layer?.insertSublayer(gradient, at: 0)

overlayView has nothing called mask, and I don't know what to mask to

    overlayView.mask = SOMETHING

    addSubview(overlayView)
  }
}