shouldInterceptRequest Method Not Working on iOS - Need Alternative Solution

[zitob9]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

The shouldInterceptRequest method only works on Android platforms. When attempting to intercept media URLs on iOS, this method does not function

Expected Behavior

Ideally, shouldInterceptRequest should work consistently across both Android and iOS platforms, providing a unified way to intercept network requests, particularly for media URL detection.

Steps with code example to reproduce

InAppWebView(
  initialUrlRequest: URLRequest(url: WebUri(url)),
  initialSettings: settings,
  shouldInterceptRequest: (controller, request) async {
    String url = request.url.toString();
    if (isVideoUrl(url)) {
      print("Found video URL: $url");
      // This works on Android but not on iOS
    }
    return null;
  },
)

Stacktrace/Logs

nothing

Flutter version

3.27.2

Operating System, Device-specific and/or Tool

macos; 3.27.2

Plugin version

6.1.5

Additional information

Currently trying to intercept background requests on iOS is challenging as shouldInterceptRequest only works on Android. While combining onLoadResource, shouldInterceptAjaxRequest, and shouldInterceptFetchRequest provides partial coverage, some requests might still be missed.
Could you suggest any other iOS-specific solutions or methods to reliably intercept all background requests? Perhaps there are iOS WebKit capabilities or alternative approaches that could be implemented to provide functionality similar to Android's shouldInterceptRequest?
Looking forward to your guidance on the best approach for iOS request interception.

Self grab

• I'm ready to work on this issue!

[laishere]

I don't think it's a bug. iOS WKWebView just doesn't support it.
You can try to register a service worker by injecting the js to intercept the requests.

[zitob9]

I don't think it's a bug. iOS WKWebView just doesn't support it. You can try to register a service worker by injecting the js to intercept the requests.

The funny thing is that onLoadResource works on iOS to get us m3u8 links, but on Android, it doesn't fetch those links—it only retrieves JS and CSS files. Only shouldInterceptRequest gets us the m3u8 links.

[laishere]

onLoadResource is natively supported on iOS. However, it is implemented via js on Android, you can check this:

flutter_inappwebview/flutter_inappwebview_android/android/src/main/java/com/pichillilorenzo/flutter_inappwebview_android/plugin_scripts_js/OnLoadResourceJS.java

Lines 30 to 48 in 0aaf7a0

	public static String ON_LOAD_RESOURCE_JS_SOURCE() {
	return
	"window." + FLAG_VARIABLE_FOR_ON_LOAD_RESOURCE_JS_SOURCE() + " = true;" +
	"(function() {" +
	" var observer = new PerformanceObserver(function(list) {" +
	" list.getEntries().forEach(function(entry) {" +
	" if (" + FLAG_VARIABLE_FOR_ON_LOAD_RESOURCE_JS_SOURCE() + " == null || " + FLAG_VARIABLE_FOR_ON_LOAD_RESOURCE_JS_SOURCE() + " == true) {" +
	" var resource = {" +
	" 'url': entry.name," +
	" 'initiatorType': entry.initiatorType," +
	" 'startTime': entry.startTime," +
	" 'duration': entry.duration" +
	" };" +
	" window." + JavaScriptBridgeJS.get_JAVASCRIPT_BRIDGE_NAME() + ".callHandler('onLoadResource', resource);" +
	" }" +
	" });" +
	" });" +
	" observer.observe({entryTypes: ['resource']});" +
	"})();";

As I tested on my pc using same method, it catches all network activities.
But it may not quite the same on Android WebView. I think it may be caused by the injection time.
You should check if your WebView version supports injecting js before page start loading. Otherwise it may miss some network resources.
Also it depends on inappwebview js bridge, which may not be ready too. But if you can manage to inject the js script before the page start loading, you can always save it in js variables and evaluate the results later when js bridge is ready.

[laishere]

https://developer.android.com/reference/androidx/webkit/WebViewCompat#addDocumentStartJavaScript(android.webkit.WebView,java.lang.String,java.util.Set%3Cjava.lang.String%3E)

If your webview is released after November 29, 2023, it should support addDocumentStartJavaScript. Check it via developer tools.

[laishere]

My advice is you can use both onLoadResource and shouldInterceptRequest if you mean to get the network requests other than block them.