如何使用WKScriptMessageHandler读取发送给父元素的sent消息？

class MessageHandler: NSObject, WKScriptMessageHandler {
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        // 在这里处理接收到的消息
    }
}

let configuration = WKWebViewConfiguration()
let userContentController = WKUserContentController()
let messageHandler = MessageHandler()
userContentController.add(messageHandler, name: "sent")
configuration.userContentController = userContentController

let webView = WKWebView(frame: .zero, configuration: configuration)

window.webkit.messageHandlers.sent.postMessage("Hello from JavaScript!")

func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
    if message.name == "sent" {
        let messageBody = message.body as? String
        print("Received message from JavaScript: \(messageBody ?? "")")
    }
}