swift 隐藏UITabbar顶部分割线

if #available(iOS 13.0, *) {
            let appearance = UITabBarAppearance.init()
            appearance.backgroundColor = UIColor.white
            appearance.shadowColor = UIColor.clear
            self.tabBar.standardAppearance = appearance
        } else {
            UITabBar.appearance().backgroundImage = UIImage.init()
            UITabBar.appearance().shadowImage = UIImage.init()
            UITabBar.appearance().backgroundColor = UIColor.white
        }