jkereako/ReCAPTCHAViewController.swift

## recaptcha.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <script src="https://www.google.com/recaptcha/api.js?onload=onLoad&render=explicit&hl=en" async defer></script>
    <title></title>
    <script type="text/javascript">
      const post = function(value) {
          window.webkit.messageHandlers.recaptcha.postMessage(value);
      };

      console.log = function(message) {
          post(message);
      };

      var onLoad = function() {
          grecaptcha.render(
            "recaptcha",
            {
              sitekey: "${siteKey}",
              callback: function(token) {
                  post(token);
              },
              size: "normal"
            }
          );
      };
    </script>
  </head>
  <body>
      <div id="recaptcha"></div>
  </body>
</html>

## ReCAPTCHAViewController.swift
import UIKit
import WebKit

final class ReCAPTCHAViewController: UIViewController {
    private var webView: WKWebView!
    private let viewModel: ReCAPTCHAViewModel

    init(viewModel: ReCAPTCHAViewModel) {
        self.viewModel = viewModel

        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func loadView() {
        let webConfiguration = WKWebViewConfiguration()
        let contentController = WKUserContentController()

        contentController.add(viewModel, name: "recaptcha")
        webConfiguration.userContentController = contentController

        webView = WKWebView(frame: .zero, configuration: webConfiguration)
        view = webView
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.leftBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .close,
            target: self,
            action: #selector(didSelectCloseButton)
        )

        webView.loadHTMLString(viewModel.html, baseURL: viewModel.url)
    }
}

// MARK: - Target-Actions
private extension ReCAPTCHAViewController {
    @IBAction func didSelectCloseButton() {
        dismiss(animated: true)
    }
}

## ReCAPTCHAViewModel.swift
import WebKit

protocol ReCAPTCHAViewModelDelegate: class {
    func didSolveCAPTCHA(token: String)
}

final class ReCAPTCHAViewModel: NSObject {
    weak var delegate: ReCAPTCHAViewModelDelegate?

    var html: String {
        guard let filePath = Bundle.main.path(
            forResource: "recaptcha", ofType: "html"
            ) else {
                assertionFailure("Unable to find the file.")

                return ""
        }

        let contents = try! String(
            contentsOfFile: filePath, encoding: .utf8
        )

        return parse(contents, with: ["siteKey": siteKey])
    }

    let siteKey: String
    let url: URL

    /// Creates a ReCAPTCHAViewModel
    /// - Parameters:
    ///   - siteKey: ReCAPTCHA's site key
    ///   - url: The URL for registered with Google
    init(siteKey: String, url: URL) {
        self.siteKey = siteKey
        self.url = url

        super.init()
    }
}

// MARK: - WKScriptMessageHandler
extension ReCAPTCHAViewModel: WKScriptMessageHandler {
    func userContentController(_ userContentController: WKUserContentController,
                               didReceive message: WKScriptMessage) {
        guard let message = message.body as? String else {
            assertionFailure("Expected a string")
            return
        }

        delegate?.didSolveCAPTCHA(token: message)
    }
}

private extension ReCAPTCHAViewModel {
    func parse(_ string: String, with valueMap: [String: String]) -> String {
        var parsedString = string

        valueMap.forEach { key, value in
            parsedString = parsedString.replacingOccurrences(
                of: "${\(key)}", with: value
            )
        }

        return parsedString
    }
}
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8" />
	<meta name="viewport" content="width=device-width, initial-scale=1" />
	<script src="https://www.google.com/recaptcha/api.js?onload=onLoad&render=explicit&hl=en" async defer></script>
	<title></title>
	<script type="text/javascript">
	const post = function(value) {
	window.webkit.messageHandlers.recaptcha.postMessage(value);
	};

	console.log = function(message) {
	post(message);
	};

	var onLoad = function() {
	grecaptcha.render(
	"recaptcha",
	{
	sitekey: "${siteKey}",
	callback: function(token) {
	post(token);
	},
	size: "normal"
	}
	);
	};
	</script>
	</head>
	<body>
	<div id="recaptcha"></div>
	</body>
	</html>
	import UIKit
	import WebKit

	final class ReCAPTCHAViewController: UIViewController {
	private var webView: WKWebView!
	private let viewModel: ReCAPTCHAViewModel

	init(viewModel: ReCAPTCHAViewModel) {
	self.viewModel = viewModel

	super.init(nibName: nil, bundle: nil)
	}

	required init?(coder: NSCoder) {
	fatalError("init(coder:) has not been implemented")
	}

	override func loadView() {
	let webConfiguration = WKWebViewConfiguration()
	let contentController = WKUserContentController()

	contentController.add(viewModel, name: "recaptcha")
	webConfiguration.userContentController = contentController

	webView = WKWebView(frame: .zero, configuration: webConfiguration)
	view = webView
	}

	override func viewDidLoad() {
	super.viewDidLoad()

	navigationItem.leftBarButtonItem = UIBarButtonItem(
	barButtonSystemItem: .close,
	target: self,
	action: #selector(didSelectCloseButton)
	)

	webView.loadHTMLString(viewModel.html, baseURL: viewModel.url)
	}
	}

	// MARK: - Target-Actions
	private extension ReCAPTCHAViewController {
	@IBAction func didSelectCloseButton() {
	dismiss(animated: true)
	}
	}
	import WebKit

	protocol ReCAPTCHAViewModelDelegate: class {
	func didSolveCAPTCHA(token: String)
	}

	final class ReCAPTCHAViewModel: NSObject {
	weak var delegate: ReCAPTCHAViewModelDelegate?

	var html: String {
	guard let filePath = Bundle.main.path(
	forResource: "recaptcha", ofType: "html"
	) else {
	assertionFailure("Unable to find the file.")

	return ""
	}

	let contents = try! String(
	contentsOfFile: filePath, encoding: .utf8
	)

	return parse(contents, with: ["siteKey": siteKey])
	}

	let siteKey: String
	let url: URL

	/// Creates a ReCAPTCHAViewModel
	/// - Parameters:
	/// - siteKey: ReCAPTCHA's site key
	/// - url: The URL for registered with Google
	init(siteKey: String, url: URL) {
	self.siteKey = siteKey
	self.url = url

	super.init()
	}
	}

	// MARK: - WKScriptMessageHandler
	extension ReCAPTCHAViewModel: WKScriptMessageHandler {
	func userContentController(_ userContentController: WKUserContentController,
	didReceive message: WKScriptMessage) {
	guard let message = message.body as? String else {
	assertionFailure("Expected a string")
	return
	}

	delegate?.didSolveCAPTCHA(token: message)
	}
	}

	private extension ReCAPTCHAViewModel {
	func parse(_ string: String, with valueMap: [String: String]) -> String {
	var parsedString = string

	valueMap.forEach { key, value in
	parsedString = parsedString.replacingOccurrences(
	of: "${\(key)}", with: value
	)
	}

	return parsedString
	}
	}