Swift version: 5.6
By default WKWebView
works sort of like Safari, albeit in a single view rather than having tabs. If you want something more advanced – being able to monitor opening and closing windows, override behavior for JavaScript user interface, and so on – then the WKUIDelegate
protocol is for you.
First, make your view controller conform to it by adding WKUIDelegate
to its list of protocols. Second, assign your view controller to the uiDelegate
property of your web view:
yourWebView.uiDelegate = self
Finally, implement whichever of the optional methods of WKUIDelegate
takes your interest. For example, you can make WKWebView
show a custom alert controller when any web page uses the alert()
JavaScript function:
func webView(_ webView: WKWebView, runJavaScriptAlertPanelWithMessage message: String, initiatedByFrame frame: WKFrameInfo, completionHandler: @escaping () -> Void) {
let ac = UIAlertController(title: "Hey, listen!", message: message, preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
present(ac, animated: true)
completionHandler()
}
There’s also runJavaScriptConfirmPanelWithMessage
for showing confirm and deny UI, runJavaScriptTextInputPanelWithPrompt
for requesting user text input, and so on.
Note: You must call the completion handler. JavaScript’s alerts are blocking, which means JavaScript execution will not continue until the alert finishes. As a result, WebKit will complain if you don’t let it know when you’re done.
SAVE 50% To celebrate Black Friday, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 10.0
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Link copied to your pasteboard.