修改TextField ---- PlaceHolder颜色（属性）

var attributes:[String:AnyObject] = NSMutableDictionary() as! [String:AnyObject]

      attributes[NSForegroundColorAttributeName] = UIColor.white

 let paceH:NSAttributedString = NSAttributedString.init(string: "请输入手机号！", attributes: attributes)

        Phonefiled.attributedPlaceholder = paceH