WKWebView Content loaded function never get called

You are not setting the navigationDelegate. Set it and it should be fine.

class ViewController: UIViewController, WKNavigationDelegate {


  override func viewDidLoad() {
    super.viewDidLoad()

    let noLayoutFormatOptions = NSLayoutFormatOptions(rawValue: 0)

    let webView = WKWebView(frame: CGRectZero, configuration: WKWebViewConfiguration())
    webView.setTranslatesAutoresizingMaskIntoConstraints(false)
    webView.navigationDelegate = self
    view.addSubview(webView)

    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[webView]|", options: noLayoutFormatOptions, metrics: nil, views: ["webView": webView]))

    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[webView]|", options: noLayoutFormatOptions, metrics: nil, views: ["webView": webView]))

    let url = NSURL(string: "http://google.com")
    let request = NSURLRequest(URL: url)
    webView.loadRequest(request)
  }

  func webView(webView: WKWebView!, didFinishNavigation navigation: WKNavigation!) {
    print("Finished navigating to url \(webView.url)");
  }

}

And here is a bit better version with Swift 3.

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let configuration = WKWebViewConfiguration()
        let webView = WKWebView(frame: .zero, configuration: configuration)
        webView.translatesAutoresizingMaskIntoConstraints = false
        webView.navigationDelegate = self
        view.addSubview(webView)

        [webView.topAnchor.constraint(equalTo: view.topAnchor),
         webView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
         webView.leftAnchor.constraint(equalTo: view.leftAnchor),
         webView.rightAnchor.constraint(equalTo: view.rightAnchor)].forEach  { anchor in
            anchor.isActive = true
        }

        if let url = URL(string: "https://google.com/search?q=westworld") {
            webView.load(URLRequest(url: url))
        }
    }

}

  extension ViewController: WKNavigationDelegate {

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        print("Finished navigating to url \(webView.url)")
    }

}