如何使用swift在WKWebView中预先填充网站上的文本框

import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {
    
    var webView: WKWebView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建WKWebView配置
        let config = WKWebViewConfiguration()
        webView = WKWebView(frame: self.view.frame, configuration: config)
        webView.navigationDelegate = self
        self.view.addSubview(webView)
        
        // 加载网页
        if let url = URL(string: "https://example.com") {
            let request = URLRequest(url: url)
            webView.load(request)
        }
    }
    
    // 网页加载完成后调用
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        // 注入JavaScript代码来预先填充文本框
        let jsCode = """
        var inputs = document.getElementsByTagName('input');
        for (var i = 0; i < inputs.length; i++) {
            if (inputs[i].name === 'username') {
                inputs[i].value = '预先填充的用户名';
            }
            if (inputs[i].name === 'password') {
                inputs[i].value = '预先填充的密码';
            }
        }
        """
        webView.evaluateJavaScript(jsCode, completionHandler: nil)
    }
}