Added fix for future UIWebview implementation. This has no effect at the moment because the NJKWebViewProgress does implement all UIWebView delegate methods. say there was a new method which NJKWebViewProgress did not implement. The UIWebView first checks to see if the NJKWebViewProgress implements this method and fails (it has no idea that the a _webViewProxyDelegate object exists!). So it won't forward the method to its _webViewProxyDelegate because we never check to see if the _webViewProxyDelegate responds to the selector. Fix is to override - (BOOL)respondsToSelector:(SEL)aSelector in NJKWebViewProgress and check if _webViewProxyDelegate respondsToSelector:aSelector .