local_biometrics_manager 0.1.2

Biometric authentication for Flutter on Android and iOS: fingerprint, face and iris detection, device-credential fallback, custom prompts and a live status stream.

example/lib/main.dart

import 'dart:async';

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

void main() => runApp(const ExampleApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Biometrics Demo',
      theme: ThemeData(colorSchemeSeed: Colors.indigo, useMaterial3: true),
      home: const HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final _biometrics = LocalBiometricsManager.instance;

  BiometricStatus? _status;
  String _lastResult = 'No attempt yet';
  StreamSubscription<BiometricStatus>? _statusSub;

  @override
  void initState() {
    super.initState();
    _refreshStatus();
    // Keep the on-screen status in sync with the device (enrolment, lockout…).
    _statusSub = _biometrics.onBiometricStatusChanged.listen((status) {
      if (mounted) setState(() => _status = status);
    });
  }

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

  Future<void> _refreshStatus() async {
    final status = await _biometrics.getBiometricStatus();
    if (mounted) setState(() => _status = status);
  }

  Future<void> _authenticate({bool allowFallback = false}) async {
    final result = await _biometrics.authenticate(
      BiometricRequest(
        title: 'Verify your identity',
        subtitle: 'Biometrics demo',
        description: 'Use your fingerprint or face to continue.',
        allowDeviceFallback: allowFallback,
        timeoutSeconds: 30,
        uiConfig: const BiometricUIConfig(
          negativeButtonText: 'Not now',
          primaryColorArgb: 0xFF3F51B5,
        ),
      ),
    );

    if (!mounted) return;
    setState(() {
      _lastResult = result.isSuccess
          ? 'Success via ${result.usedType?.name ?? 'biometric'}'
          : 'Failed [${result.errorCode}] ${result.errorMessage ?? ''}';
    });
  }

  @override
  Widget build(BuildContext context) {
    final status = _status;
    return Scaffold(
      appBar: AppBar(title: const Text('local_biometrics_manager')),
      body: RefreshIndicator(
        onRefresh: _refreshStatus,
        child: ListView(
          padding: const EdgeInsets.all(16),
          children: [
            _StatusCard(status: status),
            const SizedBox(height: 16),
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text('Last result',
                        style: TextStyle(fontWeight: FontWeight.bold)),
                    const SizedBox(height: 8),
                    Text(_lastResult),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 16),
            FilledButton.icon(
              onPressed: (status?.isAvailable ?? false)
                  ? () => _authenticate()
                  : null,
              icon: const Icon(Icons.fingerprint),
              label: const Text('Authenticate'),
            ),
            const SizedBox(height: 8),
            OutlinedButton.icon(
              onPressed: () => _authenticate(allowFallback: true),
              icon: const Icon(Icons.password),
              label: const Text('Authenticate (allow PIN fallback)'),
            ),
            const SizedBox(height: 8),
            TextButton.icon(
              onPressed: () => _biometrics.cancelAuthentication(),
              icon: const Icon(Icons.close),
              label: const Text('Cancel ongoing'),
            ),
          ],
        ),
      ),
    );
  }
}

/// Small widget that renders the current [BiometricStatus] in a readable card.
class _StatusCard extends StatelessWidget {
  const _StatusCard({required this.status});

  final BiometricStatus? status;

  @override
  Widget build(BuildContext context) {
    if (status == null) {
      return const Card(
        child: Padding(
          padding: EdgeInsets.all(16),
          child: Text('Reading biometric status…'),
        ),
      );
    }

    final s = status!;
    final types = s.availableTypes.map((t) => t.name).join(', ');
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            const Text('Device status',
                style: TextStyle(fontWeight: FontWeight.bold)),
            const SizedBox(height: 8),
            _row('Available', s.isAvailable ? 'Yes' : 'No'),
            _row('Enrolled', s.isEnrolled ? 'Yes' : 'No'),
            _row('Types', types.isEmpty ? '—' : types),
            if (s.lockoutStatus != null)
              _row('Locked out', s.lockoutStatus!.isLockedOut ? 'Yes' : 'No'),
            if (s.hardwareInfo?.deviceModel != null)
              _row('Device', s.hardwareInfo!.deviceModel!),
          ],
        ),
      ),
    );
  }

  Widget _row(String label, String value) => Padding(
        padding: const EdgeInsets.symmetric(vertical: 2),
        child: Row(
          children: [
            SizedBox(width: 110, child: Text(label)),
            Expanded(
              child: Text(value, style: const TextStyle(color: Colors.black87)),
            ),
          ],
        ),
      );
}