目标c - 如何在后退按钮上显示viewController的较短名称

class MyViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()

        let backButton = UIButton(type: .custom)
        backButton.setTitle("Back", for: .normal)
        backButton.addTarget(self, action: #selector(backButtonTapped), for: .touchUpInside)
        
        let viewControllerTitle = "My View Controller"
        
        let leftBarButtonItem = UIBarButtonItem(customView: backButton)
        leftBarButtonItem.title = viewControllerTitle
        
        navigationItem.leftBarButtonItem = leftBarButtonItem
    }
    
    @objc func backButtonTapped() {
        // Handle back button tap
    }
}