tvos: change focused color of TVCaptionButtonView

How to change default white color of tvos swift TVCaptionButtonView selection?

I have tried to change in this way

class MyTVCaptionButtonView: TVCaptionButtonView {
    override func didUpdateFocus(in context: UIFocusUpdateContext, with coordinator: UIFocusAnimationCoordinator) {
        let highlight = context.nextFocusedView == self
        print("highlighted \(highlight)")
        self.backgroundColor = highlight ? .red : .green
        self.contentView.backgroundColor = highlight ? .yellow : .black
    }
}

But background when button is focused is still white