从Swift中的另一个ViewController访问rightBarButton函数

class SecondViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建一个自定义的UIBarButtonItem
        let customButton = UIBarButtonItem(title: "Custom", style: .plain, target: self, action: #selector(customButtonTapped))
        navigationItem.rightBarButtonItem = customButton
    }
    
    @objc func customButtonTapped() {
        print("Custom button tapped!")
    }
}

class FirstViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 假设我们已经有了SecondViewController的实例
        let secondVC = SecondViewController()
        
        // 访问SecondViewController的rightBarButton
        if let rightBarButton = secondVC.navigationItem.rightBarButtonItem {
            print("Right bar button title: \(rightBarButton.title ?? "")")
        } else {
            print("Right bar button is nil")
        }
    }
}

class FirstViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let secondVC = SecondViewController()
        secondVC.viewDidLoad() // 确保视图加载完成
        
        if let rightBarButton = secondVC.navigationItem.rightBarButtonItem {
            print("Right bar button title: \(rightBarButton.title ?? "")")
        } else {
            print("Right bar button is nil")
        }
    }
}