TableViewの上下を透明グラデーションにする

gradient.swift

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        let gradient = CAGradientLayer()
        gradient.frame = tableView.superview?.bounds ?? .null
        gradient.colors = [UIColor.clear.cgColor, UIColor.black.cgColor, UIColor.black.cgColor, UIColor.clear.cgColor]
        gradient.locations = [0.0, 0.1, 0.9, 1.0]
        tableView.superview?.layer.mask = gradient
   }