UINavigationBar 相关问题

1. 关于更改navigationBar 透明

//此方法封装navigationBar背景透明，然后设置背景色    func navigationBarBackGround(red:CGFloat, green:CGFloat, blue:CGFloat, alpha:CGFloat) {        currentMenu?.navigationBar.setBackgroundImage(UIImage(), for: .default)        currentMenu?.navigationBar.shadowImage = UIImage()        currentMenu?.navigationBar.isTranslucent = true        currentMenu?.navigationBar.backgroundColor = UIColor.init(red: red/255.0, green: green/255.0, blue: blue/255.0, alpha: alpha)    }