Bug iOS 17.2 Beta only webView.configuration.userController.add(_ scriptMessageHandler: WKScriptMessageHandler, name: String) Not Working

Question

I have the following lines of code in our app:

@objc convenience init(webView: WKWebView, delegate: SomeDelegate, navigationDelegate: WKNavigationDelegate) {
        self.webView = webView
        self.webView.makeInspectable()
        self.webView.navigationDelegate = navigationDelegate
        self.webView.uiDelegate = self
        self.webView.configuration.suppressesIncrementalRendering = true
        self.webView.configuration.userContentController.add(weakSelf ?? self,
                                                             name: "handlerOne")
        self.webView.configuration.userContentController.add(weakSelf ?? self,
                                                             name: "handlerTwo")

       injectUserScripts() // Injects WKUserScripts into the webView.configuration.userContentController
}

My JS script looks as follows:

(function() {
            addEventListener('mousedown', function() {
                window.webkit.messageHandlers.handlerOne.postMessage('WKUserScriptMouseDown');
            }, true);
        })();

if (MyApp.getProperty("os") != null) {
                     window.webkit.messageHandlers.handlerTwo.postMessage(url);
                 } else {
                     console.log(url);
                     // non-mobile browser (for testing)
                 }

However I keep seeing an error in my Safari debugger:

TypeError: undefined is not an object (evaluating 'window.webkit.messageHandlers.handlerOne')

TypeError: undefined is not an object (evaluating 'window.webkit.messageHandlers.handlerTwo')

1.2k

Posted by

artuAtPandora

Reply

Add a Comment

Answer 1

I tried removing the custom handlers and attempted this:

(function() {
            addEventListener('mousedown', function() {
                window.webkit.messageHandlers.postMessage('WKUserScriptMouseDown');
            }, true);
        })();

I would think this broadcast the message to all the handlers?? However now I get the error message:

TypeError: undefined is not an object (evaluating 'window.webkit.messageHandlers.postMessage')

My next attempt is to wrap this line into a (function() {})(); but if someone else has an idea or is facing similar issues with iOS beta 17.2 only it would be great to hear ideas

Posted by

artuAtPandora

Add a Comment

Answer 2

I tried some other technique to debug this and get to the root of the issue, I decided to put window.webkit.messageHandlers.handlerOne.postMessage(... and window.webkit.messageHandlers.handlerTwo.postMessage(... inside an if conditional and check which is the object that is `undefined.

(function() {
            addEventListener('mousedown', function() {
              if (window.webkit && window.webkit.messageHandlers && window.webkit.messageHandlers.handlerOne) {
                   window.webkit.messageHandlers.handlerOne.postMessage('WKUserScriptMouseDown');
              }
            }, true);
        })();

After debugging this I found out that window.webkit.messageHandlers is the undefined object, which leads me to believe that webView.configuration.userContentController.add(handlerClass, name: "...") is broken on iOS 17.2 beta

hence messageHandlers is never defined, I'd appreciate to hear if this is happening to someone else with their apps.

Posted by

artuAtPandora

Add a Comment

Answer 3

Not sure if this is realated but I've had all kinds of Webview/Webkit issues in the iOS 17.2 Beta "21C5029g". Regarless of browser, I get a breif site offline error with almost every website I go to, but then they load. I've reset network settings. Did not help. The bigger inconvience is the beta broke the fuctionality of my gradio webui I use for GenAI stuff like Stable Diffusion (Automatic-1111). The WebUI functions perfectly in every other browser and device, except my iPhone 14 Pro Max with the current beta.

Posted by

Blizaine

Add a Comment

Answer 4

I have same issues in the ios 17.1 - iphone 12

Posted by

navyblue

Add a Comment

Bug iOS 17.2 Beta only webView.configuration.userController.add(_ scriptMessageHandler: WKScriptMessageHandler, name: String) Not Working

Replies