我刚开始学习flutter，正在使用webview。我创建了一个应用程序，它从文本字段中接收用户输入字符串，并在按下按钮时将其加载到webview小部件中。但是当按钮被点击时webview小部件不会更新。代码如下：

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

class WebviewScreen extends StatefulWidget {
  const WebviewScreen({super.key});

  @override
  State<WebviewScreen> createState() => _WebviewScreenState();
}

class _WebviewScreenState extends State<WebviewScreen> {
  TextEditingController urlController = TextEditingController();
  WebViewController webController = WebViewController();
  String url = 'https://google.com';

  Future<void> buttonPressed() async {
    setState(() {
      url = urlController.text;
    });
    await webController.loadHtmlString(url);
  }

  @override
  void initState() {
    urlController.text = 'https://';
    webController.loadRequest(Uri.parse(url));
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Webview App'),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.baseline,
              textBaseline: TextBaseline.ideographic,
              children: [
                Expanded(
                  child: Container(
                    margin: const EdgeInsets.symmetric(horizontal: 20),
                    child: TextField(
                      controller: urlController,
                      keyboardType: TextInputType.url,
                      decoration: const InputDecoration(
                        labelText: 'Enter URL',
                      ),
                    ),
                  ),
                ),
                TextButton(
                  onPressed: buttonPressed,
                  child: const Text(
                    'Go',
                    style: TextStyle(fontSize: 25),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 70),
            SizedBox(
              height: 500,
              width: 350,
              child: WebViewWidget(
                controller: webController,
              ),
            )
          ],
        ),
      ),
    );
  }
}

我在iOS模拟器上运行这个。
webview_flutter版本：4.2.1