OAuth2.AppAuth-iOS.SSO.Embedded.iOS-AppAuth-Basic.ViewController.WKScriptMessageHandler.swift

// ViewController.swift

// . . .

// MARK: Conforming to WKScriptMessageHandler protocol
extension ViewController: WKScriptMessageHandler {
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        print(#function)

        if message.name == "callback", let messageBody = message.body as? String, let messageBodyData = messageBody.data(using: .utf8) {
            let decoder = JSONDecoder()
            var messageBodyJson: AuthenticationResponse?

            do {
                messageBodyJson = try decoder.decode(AuthenticationResponse.self, from: messageBodyData)

                messageBodyJson?.callbacks.forEach {
                    callback in

                    if callback.type == "code" {
                        /**
                        Example action against the web content.
                        */
                        let scriptSource = "document.body.style.backgroundColor = 'lightgreen'"

                        // Example action performed in the native app.

                        let webView = self.view.viewWithTag(webViewTag) as? WKWebView

                        let alert = UIAlertController(title: "Native Prompt", message: "Enter the code. \nThe correct one is: 0000", preferredStyle: UIAlertController.Style.alert)

                        alert.addTextField() {
                            textField in

                            alert.addAction(
                                UIAlertAction(title: NSLocalizedString("Cancel", comment: "Cancel Action"), style: UIAlertAction.Style.cancel) {
                                    (_: UIAlertAction) in

                                    webView?.removeFromSuperview()
                                }
                            )

                            alert.addAction(
                                UIAlertAction(title: NSLocalizedString("Submit", comment: "Submit Action"), style: UIAlertAction.Style.default) {
                                    (_: UIAlertAction) in

                                    let newValue = textField.text?.trimmingCharacters(in: .whitespacesAndNewlines)

                                    if (newValue != "0000") {
                                        webView?.removeFromSuperview()
                                    } else {
                                        // Performing the action against the web content.
                                        webView?.evaluateJavaScript(scriptSource, completionHandler: nil)
                                    }
                                }
                            )
                        }

                        present(alert, animated: false)
                    }
                }
            } catch {
                print("Error decoding callback message: ", error.localizedDescription)
            }
        }
    }
}