WKWebView for web content display

import UIKit
import WebKit

class WebViewController: UIViewController {
    private var webView: WKWebView!
    private var progressView: UIProgressView!

    private let urlString: String

    init(urlString: String) {
        self.urlString = urlString
        super.init(nibName: nil, bundle: nil)
    }

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

    override func loadView() {
        let configuration = WKWebViewConfiguration()
        configuration.allowsInlineMediaPlayback = true

        // JavaScript message handler
        let contentController = WKUserContentController()
        contentController.add(self, name: "messageHandler")
        configuration.userContentController = contentController

        webView = WKWebView(frame: .zero, configuration: configuration)
        webView.navigationDelegate = self
        webView.uiDelegate = self
        view = webView
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        setupProgressView()
        setupObservers()
        loadURL()
    }

    private func setupProgressView() {
        progressView = UIProgressView(progressViewStyle: .default)
        progressView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(progressView)

        NSLayoutConstraint.activate([
            progressView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
            progressView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            progressView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
        ])
    }

    private func setupObservers() {
        webView.addObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress), options: .new, context: nil)
        webView.addObserver(self, forKeyPath: #keyPath(WKWebView.title), options: .new, context: nil)
    }

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "estimatedProgress" {
            progressView.progress = Float(webView.estimatedProgress)
            progressView.isHidden = webView.estimatedProgress == 1.0
        } else if keyPath == "title" {
            title = webView.title
        }
    }

    private func loadURL() {
        guard let url = URL(string: urlString) else { return }
        let request = URLRequest(url: url)
        webView.load(request)
    }

    // MARK: - JavaScript Execution
    func executeJavaScript(_ script: String, completion: ((Any?, Error?) -> Void)? = nil) {
        webView.evaluateJavaScript(script, completionHandler: completion)
    }

    deinit {
        webView.removeObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress))
        webView.removeObserver(self, forKeyPath: #keyPath(WKWebView.title))
    }
}

// MARK: - WKNavigationDelegate
extension WebViewController: WKNavigationDelegate {
    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        if let url = navigationAction.request.url {
            // Handle custom URL schemes
            if url.scheme == "myapp" {
                print("Handle custom URL: \(url)")
                decisionHandler(.cancel)
                return
            }

            // Block certain domains
            if url.host == "blocked.com" {
                decisionHandler(.cancel)
                return
            }
        }

        decisionHandler(.allow)
    }

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        print("Finished loading")

        // Inject JavaScript
        let js = """
        window.webkit.messageHandlers.messageHandler.postMessage({
            action: 'pageLoaded',
            url: window.location.href
        });
        """
        executeJavaScript(js)
    }

    func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
        print("Failed to load: \(error.localizedDescription)")
    }
}

// MARK: - WKUIDelegate
extension WebViewController: WKUIDelegate {
    func webView(_ webView: WKWebView, runJavaScriptAlertPanelWithMessage message: String, initiatedByFrame frame: WKFrameInfo, completionHandler: @escaping () -> Void) {
        let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "OK", style: .default) { _ in
            completionHandler()
        })
        present(alert, animated: true)
    }
}

// MARK: - WKScriptMessageHandler
extension WebViewController: WKScriptMessageHandler {
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        guard let dict = message.body as? [String: Any],
              let action = dict["action"] as? String else {
            return
        }

        switch action {
        case "pageLoaded":
            if let url = dict["url"] as? String {
                print("Page loaded: \(url)")
            }
        default:
            print("Unknown action: \(action)")
        }
    }
}