按下TabBarItem时执行操作

class ViewController: UIViewController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UITabBarController实例
        let tabBarController = UITabBarController()
        
        // 设置代理为当前视图控制器
        tabBarController.delegate = self
        
        // 创建并设置各个视图控制器
        let viewController1 = UIViewController()
        viewController1.tabBarItem = UITabBarItem(title: "Tab 1", image: UIImage(named: "tab1"), tag: 0)
        
        let viewController2 = UIViewController()
        viewController2.tabBarItem = UITabBarItem(title: "Tab 2", image: UIImage(named: "tab2"), tag: 1)
        
        tabBarController.viewControllers = [viewController1, viewController2]
        
        // 将UITabBarController设置为当前视图控制器的子视图控制器
        addChild(tabBarController)
        view.addSubview(tabBarController.view)
        tabBarController.didMove(toParent: self)
    }
    
    // UITabBarControllerDelegate方法，处理选项卡点击事件
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        if tabBarController.selectedIndex == 0 {
            // 执行选项卡1的操作
            print("执行选项卡1的操作")
        } else if tabBarController.selectedIndex == 1 {
            // 执行选项卡2的操作
            print("执行选项卡2的操作")
        }
    }
}