快速改变Uitabcontroller的外观？

// 实现UITabBarControllerDelegate协议
class ViewController: UIViewController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置代理
        self.tabBarController?.delegate = self
    }
    
    // 监听选项卡选择事件
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        // 获取当前选中的选项卡
        if let selectedIndex = tabBarController.viewControllers?.firstIndex(of: viewController) {
            // 修改选项卡的外观
            let tabBarItem = tabBarController.tabBar.items?[selectedIndex]
            tabBarItem?.title = "新标题"
            tabBarItem?.image = UIImage(named: "新图标")
            tabBarItem?.selectedImage = UIImage(named: "新选中图标")
        }
    }
}

class CustomTabBar: UITabBar {
    override func layoutSubviews() {
        super.layoutSubviews()
        
        // 自定义选项卡的布局
        // ...
    }
    
    override func draw(_ rect: CGRect) {
        // 绘制自定义的背景图片
        // ...
    }
}

let tabBarController = UITabBarController()
tabBarController.tabBar = CustomTabBar()