Getting the link URL tapped in WKWebView

You can use WKWebView delegate method. And don't forget to set the webview delegate to self: webview.navigationDelegate = self

func webView(webView: WKWebView, decidePolicyForNavigationAction navigationAction: WKNavigationAction, decisionHandler: ((WKNavigationActionPolicy) -> Void)) {

    switch navigationAction.navigationType {
        case .LinkActivated:
        if navigationAction.targetFrame == nil {
            self.webView?.loadRequest(navigationAction.request)// It will load that link in same WKWebView
        }
        default:
            break
    }

    if let url = navigationAction.request.URL {
        print(url.absoluteString) // It will give the selected link URL

    }
    decisionHandler(.Allow)
}

Change addObserver like this

webView.addObserver(self, forKeyPath: "URL", options: [.new, .old], context: nil)

In observeValue function you able get both value

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if let newValue = change?[.newKey] as? Int, let oldValue = change?[.oldKey] as? Int, newValue != oldValue {
        //Value Changed
        print(change?[.newKey])
    }else{
        //Value not Changed
        print(change?[.oldKey])
    }
}

Swift 5.0

Remember to set navigationDelegate on the WKWebView instance.

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    print(String(describing: navigationAction))
    decisionHandler(.allow)
}