当视图控制器被置于视图堆栈的顶部时,如何让视图控制器运行更新代码？

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    // 在这里编写更新代码
}

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    // 在这里编写更新代码
}

class MyViewController: UIViewController, UINavigationControllerDelegate {
    // ...

    override func viewDidLoad() {
        super.viewDidLoad()
        navigationController?.delegate = self
    }

    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
        if viewController === self {
            // 在这里编写更新代码
        }
    }
}