How to do JavaScript callback from Swift?

I am loading a local html file with this inside <script>

window.webkit.messageHandlers.MyHandler.postMessage("hello");

What changes do i need on my swift file to handle setup this handler?

my current swift file :

struct WebView: UIViewRepresentable {
    var url: URL

    ...

    func makeUIView(context: Context) -> WKWebView {
        // do configuration here

        let view = WKWebView()
        view.navigationDelegate = context.coordinator
        view.load(URLRequest(url: url))

        return view
    }
    ...

Thanks.

Tried this:

    func makeUIView(context: Context) -> WKWebView {
        
        let userController = WKUserContentController()
        userController.add(self, name: "MyHandler")
        let configuration = WKWebViewConfiguration()
        configuration.userContentController = userController
        return WKWebView(frame: frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, idealHeight: 500, maxHeight: .infinity) as! CGRect, configuration: configuration)

but i'm getting error on self: Argument type 'WebView' does not conform to expected type 'WKScriptMessageHandler'