用您自己的图像替换后退按钮的最佳方式

这样做的：

class CustomViewController: UIViewController, UIGestureRecognizerDelegate {

    // MARK: - View Lifecycle

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.

        addBackButton()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        navigationController?.interactivePopGestureRecognizer?.isEnabled = true
    }

    // MARK: - UI Events

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

    // MARK: - Private Methods

    private func addBackButton() {
        let button = UIButton(type: .custom)
        button.setImage(UIImage(named: "iconNavBack"), for: .normal)
        button.addTarget(self, action: #selector(backButtonTapped), for: .touchUpInside)

        var buttonFrame = button.frame
        var buttonHeight: CGFloat = 44
        if let navBarHeight = navigationController?.navigationBar.frame.size.height {
            buttonHeight = navBarHeight
        }
        buttonFrame.size = CGSize(width: 44, height: buttonHeight)

        // button.layer.borderWidth = 1
        // button.layer.borderColor = UIColor.orange.cgColor

        button.frame = buttonFrame
        button.contentEdgeInsets = UIEdgeInsets(top: 0, left: -24, bottom: 0, right: 0) // NOTE: сдвигаем левее не саму кнопку, но изображение на ней (если нужно подвинуть по дизайну)

        navigationItem.leftBarButtonItem = UIBarButtonItem(customView: button)

        self.navigationController?.interactivePopGestureRecognizer?.delegate = self
    }

}

额外：关于如何更改标准后退按钮的图像以及如何定位它的一些建议：

https://sarunw.com/posts/how-to-change-back-button-image/