func setNavigationApperance(){

        //自定义导航栏颜色

        [self.navigationController?.navigationBar.barTintColor = UIColor (red:/255.0, green:/255.0, blue:/255.0 ,alpha:)];

        //修改左右item字体颜色

        self.navigationController?.navigationBar.tintColor = UIColor.whiteColor()

        //修改导航栏标题字体大小和颜色

        self.navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName :UIColor.whiteColor()]

    }