dependencies:
  flutter:
    sdk: flutter
  firebase_core: "^1.1.0"

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  return runApp(ProviderScope(child: MyApp()));
}

# ...
target 'Runner' do
  pod 'FirebaseFirestore', :git => 'https://github.com/invertase/firestore-ios-sdk-frameworks.git', :tag => '7.3.0'
# ...
end

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
apply plugin: 'com.google.gms.google-services' ←これを記載

~~~~~
dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation platform('com.google.firebase:firebase-bom:27.0.0') ←これを記載
    implementation 'com.google.firebase:firebase-analytics-ktx'　←これを記載
}

    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3' ← これを記載
    }

dependencies:
  firebase_auth: "^1.1.1"

FirebaseAuth.instance.signInWithEmailAndPassword({required String email, required String password})

Future<bool> signIn(String email, String password) async {
    try {
      await _auth.signInWithEmailAndPassword(
          email:email, password:password);
      return true;
    } catch (e) {
      print(e);
      return false;
    }
  }

FirebaseAuth.instance
  .authStateChanges()
  .listen((User user) {
    if (user == null) {
      print('User is currently signed out!');
    } else {
      print('User is signed in!');
    }
  });

User user = FirebaseAuth.instance.currentUser;

Future<UserCredential> createUserWithEmailAndPassword(
{required String email,
required String password}
)

Future<bool> signUp(String email, String password) async {
    try {
      await _auth.createUserWithEmailAndPassword(
          email:email, password: password);
      return true;
    } on FirebaseAuthException catch (e) {
      print(e);
      return false;
    } catch (e) {
      print(e);
      return false;
    }
  }

dependencies:
  crypto: ^3.0.1
  google_sign_in: ^5.0.2

/// Generates a cryptographically secure random nonce, to be included in a
/// credential request.
String generateNonce([int length = 32]) {
  final charset =
      '0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._';
  final random = Random.secure();
  return List.generate(length, (_) => charset[random.nextInt(charset.length)])
      .join();
}

/// Returns the sha256 hash of [input] in hex notation.
String sha256ofString(String input) {
  final bytes = utf8.encode(input);
  final digest = sha256.convert(bytes);
  return digest.toString();
}

@override
  Future<bool> signInWithApple() async {
    final rawNonce = NonceString.generateNonce();
    final nonce = Sha256String.sha256ofString(rawNonce);
    try {
      // Appleのサインイン
      final appleCredential = await SignInWithApple.getAppleIDCredential(
        scopes: [
          AppleIDAuthorizationScopes.email,
          AppleIDAuthorizationScopes.fullName,
        ],
        nonce: nonce,
      );

      final oauthCredential = OAuthProvider('apple.com').credential(
        idToken: appleCredential.identityToken,
        rawNonce: rawNonce,
      );

      await _auth.signInWithCredential(oauthCredential);
      return true;
    } catch (e) {
      print(e);
      return false;
    }
  }

$ brew install nodebrew
$ nodebrew -v
nodebrew 1.1.0

Fetching: https://nodejs.org/dist/v15.7.0/node-v15.7.0-darwin-x64.tar.gz
Warning: Failed to create the file 
Warning: /Users/XXXX/.nodebrew/src/v15.7.0/node-v15.7.0-darwin-x64.tar.gz: No 
Warning: such file or directory

curl: (23) Failed writing body (0 != 978)
download failed: https://nodejs.org/dist/v15.7.0/node-v15.7.0-darwin-x64.tar.gz

$ mkdir -p ~/.nodebrew/src

$ nodebrew install-binary latest

Fetching: https://nodejs.org/dist/v16.1.0/node-v16.1.0-darwin-x64.tar.gz
########################################################################################################################################################## 100.0%
Installed successfully

$ nodebrew list
v16.1.0

$ nodebrew use v16.1.0
use v16.1.0

export PATH=$PATH:$HOME/.nodebrew/current/bin

$ node -v
v16.1.0

$ npm -v
7.11.2

$ npm install -g firebase-tools

$ firebase -V
9.10.2

$ firebase login

? Allow Firebase to collect CLI usage and error reporting information? (Y/n) 

✔  Success! Logged in as <アカウント>

$ firebase logout

$ firebase projects:list

$ firebase init

$ firebase emulators:start

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsLocalNetworking</key>
    <true/>
</dict>

FirebaseAuth.instance.useEmulator('http://localhost:9099');

dependencies:
  flutter:
    sdk: flutter
  firebase_core: ^1.1.0
  firebase_analytics: ^8.0.3
  firebase_crashlytics: ^2.0.2

$ pod update

buildscript {
    
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3'
        // これ記載↓
        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.5.1'
    }
}

apply plugin: 'com.google.firebase.crashlytics'

void showAlertDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text(
            '危険',
            style: const TextStyle(
              color: Colors.red,
              fontWeight: FontWeight.bold,
            ),
          ),
          content: const Text(
            'クラッシュさせますか？',
          ),
          actions: <Widget>[
            TextButton(
              onPressed: () {
                AppLogger.logger.d('crash');

                FirebaseCrashlytics.instance.setCustomKey('test', 'crashTest');
                FirebaseCrashlytics.instance.crash();
              },
              style: TextButton.styleFrom(
                primary: Colors.red,
              ),
              child: const Text('はい'),
            ),
            TextButton(
              onPressed: () => Navigator.pop(context),
              style: TextButton.styleFrom(
                primary: Colors.black,
              ),
              child: const Text('いいえ'),
            ),
          ],
        );
      },

FirebaseCrashlytics.instance.crash();

FirebaseCrashlytics.instance.setCustomKey('test', 'crashTest');

await FirebaseCrashlytics.instance
      .setCrashlyticsCollectionEnabled(false);

 FlutterError.onError = FirebaseCrashlytics.instance.recordFlutterError;

runZonedGuarded(() {
    runApp(ProviderScope(child: MyApp()));
  }, (error, stackTrace) {
    FirebaseCrashlytics.instance.recordError(error, stackTrace);
  });

$ flutter run --release  

# 例
$ xcodebuild -showBuildSettings | grep "SRC\|PROJECT"

mdfind -name .dSYM | while read -r line; do dwarfdump -u "$line"; done | grep <dSYMのUUID>

$ ~<Podsフォルダがあるディレクトリまでのパス>/Pods/FirebaseCrashlytics/upload-symbols -gsp ~<GoogleService-Info.plistがあるディレクトリまでのパス>/GoogleService-Info.plist -p ios <dSYMがあるパス>

dependencies:
  flutter:
    sdk: flutter
  firebase_performance: ^0.7.0+2

dependencies:
  flutter:
  firebase_messaging: ^10.0.0
  flutter_local_notifications: ^5.0.0+4

// iOSのプッシュ通知の設定リクエスト
  await messaging.requestPermission(
    alert: true,
    announcement: false,
    badge: true,
    carPlay: false,
    criticalAlert: false,
    provisional: false,
    sound: true,
  );

// iOS のプッシュ通知のフォアグラウンドの表示
  await FirebaseMessaging.instance.setForegroundNotificationPresentationOptions(
    alert: true,
    badge: true,
    sound: true,
  );

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // アプリケーションコンテキスト外のIsolateで実行しているため
  // ここでアプリケーションの状態やUIの更新はしてはダメ
  // ドキュメントより
  await Firebase.initializeApp();
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();

  // バックグラウンド時
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
}

class NotificationChannel {
  static const androidChannel = AndroidNotificationChannel(
    'high_importance_channel',
    'High Importance Notifications',
    'This channel is used for important notifications.',
    importance: Importance.max,
  );
}

// Androidのチャンネル指定
await flutterLocalNotificationsPlugin
      .resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin>()
      ?.createNotificationChannel(NotificationChannel.androidChannel);

<meta-data
                android:name="com.google.firebase.messaging.default_notification_channel_id"
                android:value="@string/default_notification_channel_id"
                />

final flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      print('Got a message whilst in the foreground!');
      print('Message data: ${message.data}');

      final notification = message.notification;
      final android = message.notification?.android;

      final channel = NotificationChannel.androidChannel;

      if (notification != null && android != null) {
        print(notification.body);
        FlutterLocalNotificationsPlugin().show(
          notification.hashCode,
          notification.title,
          notification.body,
          NotificationDetails(
            android: AndroidNotificationDetails(
              channel.id,
              channel.name,
              channel.description,
              icon: 'launch_background',
            ),
          ),
        );
      }
    });

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // アプリケーションコンテキスト外のIsolateで実行しているため
  // ここでアプリケーションの状態やUIの更新はしてはダメ
  // ドキュメントより
  await Firebase.initializeApp();
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();

  // バックグラウンド時
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
}

dependencies:
  flutter:
    sdk: flutter
  firebase_in_app_messaging: ^0.5.0+4