I have a
func webView(webView: WKWebView, didCommitNavigation navigation: WKNavigation!)
As this verifies, the & is not automatically escaped in the usual way, so you probably have to process your search string manually (wherever your user enters the terms, just replace the & when you get it from there):
let searchterm = getTermFromWherever() let actualterm = searchterm.stringByReplacingOccurrencesOfString("&", withString: "%26")
This should work.