如何在UIWebView中关闭页面并返回应用程序

override func navigationBar(_ navigationBar: UINavigationBar, didPushItem button: UIBarButtonItem) {
    if navigationBar.topItem === button.item {
        // 返回到应用程序
    }
}

webView.stopLoading()
webView.delegate = nil
webView.removeFromSuperview()
webView = nil

navigationController?.popViewController(animated: true)

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {

    var webView: WKWebView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let webConfiguration = WKWebViewConfiguration()
        webView = WKWebView(frame: .zero, configuration: webConfiguration)
        webView.navigationDelegate = self
        view.addSubview(webView)

        let myURL = URL(string:"https://www.example.com")
        let myRequest = URLRequest(url: myURL!)
        webView.load(myRequest)
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        webView.frame = view.bounds
    }

    override func navigationBar(_ navigationBar: UINavigationBar, didPushItem button: UIBarButtonItem) {
        if navigationBar.topItem === button.item {
            // 返回到应用程序
            webView.stopLoading()
            webView.navigationDelegate = nil
            webView.removeFromSuperview()
            webView = nil
            navigationController?.popViewController(animated: true)
        }
    }
}