WebKit Observer: URL

URLObserver.swift

var webViewURLObserver: NSKeyValueObservation?

override func viewDidLoad() {
    super.viewDidLoad()
    
    webViewURLObserver = webView.observe(\.url, options: .new) { [weak self] webView, change in
        let url = "\(String(describing: change.newValue))"
        self?.urlDidChange(urlString: url)
    }
}

func urlDidChange(urlString: String) {
    if let url = urlString as? String {
        if url.contains("404") {
            print("Error 404: Page not found")
        }
    }
}