Firebase Auth in a Flutter app with WebView

Question

I'm developing a Flutter app that uses Firebase Auth to handle authentication. However, some sections of the app use a WebView that shows content from the web version (which also uses Firebase Auth). My question is to how ensure that users that have signed in to the app are also signed in within the WebView.

Answer 1

There's nothing built into Firebase to automatically synchronize the authentication state from native code into a web view that is opened from this native code.

It should be possible to pass the ID token from the native code to the web view and use it there, but I've never tried that myself.

Some relevant links that I found:

• How to pass Firebase Auth token to webView and register for notifications on Android (describes the same problem, but then with Android - and unfortunately without an answer)
• Is there a way to keep the user signed in between native code and a WebView using Firebase Auth on Android? (unfortunately also without an answer)
• Webviews and social authentication with React Native (blog post describing a workaround for this type of problem with Facebook login and react native)
• How to do Authentication on native and pass to webView? (also with React Native, but this answer looks promising)
• capacitor-firebase-auth npm module (plugin for Capacitor framework that propagates the token from native code to web view)

None of these are pre-built solutions for Flutter + WebView, but I hope that combined they allow you to build something yourself. If you do: please share it! :)