如何在wkwebview中通过iframe在html文件中加载本地文件？

let webView = WKWebView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height))
view.addSubview(webView)

if let url = Bundle.main.url(forResource: "index", withExtension: "html") {
    webView.loadFileURL(url, allowingReadAccessTo: url.deletingLastPathComponent())
}

extension ViewController: WKUIDelegate, WKNavigationDelegate {
    // 处理创建新窗口的请求
    func webView(_ webView: WKWebView, createWebViewWith configuration: WKWebViewConfiguration, for navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
        if navigationAction.targetFrame == nil {
            webView.load(navigationAction.request)
        }
        return nil
    }
    
    // 允许加载请求
    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        decisionHandler(.allow)
    }
}

// 设置WKWebView的UIDelegate和NavigationDelegate
webView.uiDelegate = self
webView.navigationDelegate = self