Swift在一个应用程序中使用多个TabBarControllers

class MyViewController: UIViewController {
    var data: [String] = []

    override func viewDidLoad() {
        super.viewDidLoad()
        loadDataIfNeeded()
    }

    func loadDataIfNeeded() {
        if data.isEmpty {
            // 模拟数据加载
            DispatchQueue.global().async {
                self.data = self.fetchData()
                DispatchQueue.main.async {
                    self.updateUI()
                }
            }
        }
    }

    func fetchData() -> [String] {
        // 模拟数据加载过程
        sleep(2)
        return ["Item 1", "Item 2", "Item 3"]
    }

    func updateUI() {
        // 更新UI
    }
}

let tabBarController = UITabBarController()
tabBarController.tabBar.isTranslucent = false
tabBarController.tabBar.barTintColor = .white

// 添加多个视图控制器
let vc1 = UIViewController()
vc1.tabBarItem = UITabBarItem(title: "Home", image: UIImage(named: "home"), tag: 0)

let vc2 = UIViewController()
vc2.tabBarItem = UITabBarItem(title: "Settings", image: UIImage(named: "settings"), tag: 1)

tabBarController.viewControllers = [vc1, vc2]

class MyViewController: UIViewController {
    var savedState: String?

    override func viewDidLoad() {
        super.viewDidLoad()
        restoreStateIfNeeded()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        saveState()
    }

    func saveState() {
        savedState = "Some state data"
    }

    func restoreStateIfNeeded() {
        if let state = savedState {
            // 恢复状态
        }
    }
}