IOS UIWebView: How to add listeners to DOM events?

Question

How can I add listeners to DOM events in UIWebView? For example for the following html:

Try it
         


        

Answer 1

Here is the Swift way to intercept when a Link is clicked in the UIWebView:

Get yourself a delegate:

class ViewController: UIViewController, UIWebViewDelegate { //... }

And assign it:

override func viewDidLoad() {
        super.viewDidLoad()

        webView.delegate = self

        //...
}

Now we can use it to intercept:

    func webViewDidFinishLoad(_ webView: UIWebView) {
            if (currentURL?.lowercased().range(of:"some/url") != nil) {
                webView.stringByEvaluatingJavaScript(from: "document.getElementsByTagName('a')[0].onclick = function() {window.location = 'injected://loadPDF1'; return false;}")
            }
    }

    // Sent before a web view begins loading a frame.
    func webView(_: UIWebView, shouldStartLoadWith: URLRequest, navigationType: UIWebViewNavigationType) -> Bool{
        // intercept all injected page calls
        if (shouldStartLoadWith.url?.scheme == "injected") {
            return false;
        }
        return true;
    }