如何使用UINavigationController的自定义视图创建backBarButtomItem

import UIKit

class MyViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let customBackButton = UIButton(type: .system)
        customBackButton.setTitle("返回", for: .normal)
        customBackButton.sizeToFit()
        customBackButton.addTarget(self, action: #selector(backButtonTapped), for: .touchUpInside)

        let backItem = UIBarButtonItem(customView: customBackButton)
        self.navigationItem.leftBarButtonItem = backItem
    }

    @objc func backButtonTapped() {
        self.navigationController?.popViewController(animated: true)
    }
}