flutter_appauth causing MacOS client unable to receive Google Sign In Deep Link

[oliverbytes]

Describe the bug
I'm happy to read that native Google sign-in is now here. Unfortunately, it only works on all platforms but MacOS. I can confirm that when you add the flutter_appauth package it makes a conflict—resulting in deep links not getting received by the macOS client.

To Reproduce
Steps to reproduce the behavior:

1. Using the latest supabase package version
2. Make sure you've implemented all instructions
3. Sign in to Google

Expected behavior
The macOS client should receive the deep link and continue authentication.

Version (please complete the following information):
On Linux/macOS

├── supabase_auth_ui 0.2.1
│   └── supabase_flutter...
├── supabase_flutter 1.10.9
│   ├── supabase 1.9.7
│   │   ├── functions_client 1.3.2
│   │   ├── gotrue 1.11.0
│   │   ├── postgrest 1.3.3
│   │   ├── realtime_client 1.1.1
│   │   ├── storage_client 1.5.1

Additional context
None

[dshukertjr]

@oliverbytes
Could you share more detailed step by step instructions on how one could reproduce the issue you are experiencing?

[romaingyh]

@oliverbytes Could you share more detailed step by step instructions on how one could reproduce the issue you are experiencing?

I confirm the issue. uriLinkStream events from app_links are not fired on macos when flutter_appauth is in depencies. Here is the simplest way to illustrate:

flutter create --platforms=ios,macos deeplinks
cd deeplinks 
flutter pub add app_links flutter_appauth

Open ios/Runner/Info.plist and macos/Runner/Info.plist and add this :

	<key>CFBundleURLTypes</key>
	<array>
		<dict>
			<key>CFBundleURLName</key>
			<string>deeplinkstest</string>
			<key>CFBundleURLSchemes</key>
			<array>
				<string>deeplinks</string>
			</array>
		</dict>
	</array>

Inside lib/main.dart:

import 'dart:async';

import 'package:app_links/app_links.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: Colors.deepPurple,
          brightness: Brightness.dark,
        ),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late final StreamSubscription<Uri> _linkSubscription;
  final List<Uri> _links = [];

  @override
  void initState() {
    super.initState();

    _linkSubscription = AppLinks().uriLinkStream.listen((uri) {
      debugPrint('Got uri: $uri');
      setState(() => _links.add(uri));
    });
  }

  @override
  void dispose() {
    super.dispose();
    _linkSubscription.cancel();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(widget.title)),
      body: ListView.builder(
        itemCount: _links.length,
        itemBuilder: (context, index) {
          final uri = _links[index];
          return ListTile(
            title: Text(uri.toString()),
          );
        },
      ),
    );
  }
}

Now you can run the apps, if you open deeplinks://test in the iOS simulator it's handled, but if you click the link on macos nothing happens

[romaingyh]

Hello,

Unfortunately it appears that app_links and flutter_appauth are strongly incompatible on macos.

They both use setEventHandler method from NSAppleEventManager and from Apple Documentation :

Each application has at most one instance of NSAppleEventManager

If an event handler is already registered for the specified event class and event ID, removes it

I don't know if there is a workaround but it explains the issue now

[oliverbytes]

setEventHandler

Thanks for getting to the root of the problem. So it appears Supabase both uses app_links and recommends flutter_appauth, which are incompatible. I hope they make a solution to this ASAP.

[oliverbytes]

I unknowingly disabled this code from flutter_appauth's source for the macOS plugin and voila! Everything works as expected! 😂 Thanks for the hint @romaingyh

I made a fork incase anyone wants it. Below is how to use it

flutter_appauth:
    git:
      url: https://github.com/oliverbytes/flutter_appauth.git
      path: flutter_appauth

[oliverbytes]

Temporarily force-upgrading the underlying app_links version below fixes the issue

dependency_overrides:
  app_links: ^3.5.0