Flutter Cognito Plugin

An AWS Cognito plugin for flutter. Supports both iOS and Android.

Installation

First follow the regular flutter plugin installation on Dart Pub.

Make sure you have built the app once for both Android/iOS before continuing.

Since this plugin uses the native AWS sdk, the installation is a little more involved.

Android

Add an awsconfiguration.json file to android/app/src/main/res/raw/awsconfiguration.json.

This is what one should look like :-

{
    "IdentityManager": {
        "Default": {}
    },
    "CredentialsProvider": {
        "CognitoIdentity": {
            "Default": {
                "PoolId": "XX-XXXX-X:XXXXXXXX-XXXX-1234-abcd-1234567890ab",
                "Region": "XX-XXXX-X"
            }
        }
    },
    "CognitoUserPool": {
        "Default": {
            "PoolId": "XX-XXXX-X_abcd1234",
            "AppClientId": "XXXXXXXX",
            "AppClientSecret": "XXXXXXXXX",
            "Region": "XX-XXXX-X"
        }
    }
}

This plugin supports the amplify SDK for android and iOS, and the the amplify cli can be used to generate the awsconfiguration.json file.

Just do $ amplify init from the android & ios folder of your app.

iOS

Run $ pod init from the ios folder of your app.

Now, open ios/Podfile. Ensure ios version is set to a minimum of 9.0.

platform :ios, '9.0'

To add the awsconfiguration.json file to iOS module, you will unfortunately, need to open up your project in XCode.

1. Start Xcode
2. Click on ‘File > Open’
3. Select the ios/Runner.xcworkspace file.

Now just drag-drop the awsconfiguration.json file, from android/app/src/main/res/raw/awsconfiguration.json to XCode Runner (Right next to AppDelegate.swift).

Here is a video.

That should create a symlink to the file in the ios module, and bundle it into the final ios app.

This way you won't need to maintain 2 config files.

Hosted UI

The Hosted UI feature is needed for using Social login. Unfortunately, this requires you to modify native code in your app.

First, add the following section to android/app/src/main/res/raw/awsconfiguration.json -

("myapp://callback" and "myapp://signout" are custom urls you can provide in the "App client settings" section of Cognito User Pools)

{
  ...

  "Auth": {
    "Default": {
      "OAuth": {
        "WebDomain": "XXX.auth.ap-south-1.amazoncognito.com",
        "AppClientId": "XXXXXXXX",
        "AppClientSecret": "XXXXX"
        "SignInRedirectURI": "myapp://callback",
        "SignOutRedirectURI": "myapp://signout",
        "Scopes": ["email, "openid"]
      }
    }
  }
}

Android

1. Open your app's andorid/app/src/main/com/kotlin/.../MainActivity.kt and replace FlutterActivity() by CognitoPluginActivity("<url scheme>").

Here's what it should look like -

package ...

import androidx.annotation.NonNull
import com.pycampers.flutter_cognito_plugin.CognitoPluginActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity : CognitoPluginActivity("myapp") {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

2. Add the following to android/app/src/main/AndroidManifest.xml -

<manifest ...>
        <application ...>
            ...

            <!-- Add this section for AWS Cognito hosted UI-->
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />

                <data android:scheme="myapp" />
            </intent-filter>

        </application>
</manifest>

iOS

1. Open you apps's ios/Runner/AppDelegate.swift, and replace FlutterAppDelegate with CognitoPluginAppDelegate.

Here's what it should look like -

import Flutter
import flutter_cognito_plugin
import UIKit

@UIApplicationMain
@objc class AppDelegate: CognitoPluginAppDelegate {
    override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        GeneratedPluginRegistrant.register(with: self)
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
}

2. Add the following to ios/Runner/Info.plist

<plist version="1.0">
<dict>
    <!-- YOUR OTHER PLIST ENTRIES HERE -->

    <!-- ADD AN ENTRY TO CFBundleURLTypes for Cognito Auth -->
    <!-- IF YOU DO NOT HAVE CFBundleURLTypes, YOU CAN COPY THE WHOLE BLOCK BELOW -->
    <key>CFBundleURLTypes</key>
    <array>
        <dict>
            <key>CFBundleURLSchemes</key>
            <array>
                <string>myapp</string>
            </array>
        </dict>
    </array>
</dict>
</array>

<!-- ... -->
</dict>

Dart

Once the native setup is complete, you can use the following in your flutter app to launch the Hosted UI -

Cognito.showSignIn(
  identityProvider: "Cognito",
  scopes: ["email", "openid"],
);

Usage

The plugin comes with a showcase app that will let you try all features -- given that you setup the awsconfiguration.json correctly.

It's present in the usual example directory

$ git clone https://github.com/pycampers/flutter_cognito_plugin.git
$ cd flutter_cognito_plugin/example
$ flutter run

AppSync

You can use AWS AppSync GraphQL API using this plugin easily. Just pass in the query as a String, and the query variables!

import 'dart:convert';
import 'dart:io';

import 'package:flutter_cognito_plugin/flutter_cognito_plugin.dart';
import 'package:http/http.dart' as http;

static Future<Map> query(
  String query,
  Map<String, dynamic> variables,
) async {
  final tokens = await Cognito.getTokens();

  final response = await http.post(
    graphQLEndpoint,
    headers: {
      HttpHeaders.authorizationHeader: tokens.accessToken,
      HttpHeaders.contentTypeHeader: ContentType.json.mimeType,
    },
    body: jsonEncode({
      "query": query,
      "variables": variables,
    }),
  );

  if (response.statusCode == HttpStatus.ok) {
    return jsonDecode(response.body);
  }

  print(
    "http request failed! { statusCode: ${response.statusCode}, body: ${response.body} }",
  );
  return null;
}