Setup

class ViewController: UIViewController, WKScriptMessageHandler {
  override func viewDidLoad() {
    let contentController = WKUserContentController()

    // subscribe to LoyaltyLion events
    contentController.add(self, name: "sdkReady")

    // continue creating WKWebView instance...
  }

  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
    if message.name == "ready" {
      print("LoyaltyLion SDK is ready")
    }
  }
}

class MainActivity : AppCompatActivity() {
    lateinit var webView: WebView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        webView = WebView(this)
        setContentView(webView)

        webView.settings.javaScriptEnabled = true
        webView.addJavascriptInterface(LoyaltyLionBridge(), "LoyaltyLionBridge")

        webView.loadDataWithBaseURL(null, "...", "text/html", "utf-8", null)
    }

    inner class LoyaltyLionBridge {
        @JavascriptInterface
        fun sdkReady() {
            Log.d("WebView", "LoyaltyLion SDK ready")
        }
    }
}