New Example - Biometrics (#119)

biometrics/lib/biometrics_verifier.dart

@@ -0,0 +1,34 @@
+import 'package:flutter/services.dart';
+import 'package:local_auth/local_auth.dart';
+
+class BiometricsVerifier {
+  late LocalAuthentication auth;
+
+  BiometricsVerifier() {
+    auth = LocalAuthentication();
+  }
+
+  Future<void> _ableToAuthenticate() async {
+    bool supported = await auth.canCheckBiometrics;
+    bool entryExists = await auth.isDeviceSupported();
+    if (!supported) throw "Device doesn't support Biometrics.";
+    if (!entryExists) throw "Biometric entry not found in phone.";
+  }
+
+  Future<void> verifyBiometrics(String? prompt) async {
+    await _ableToAuthenticate();
+    late bool didAuthenticate;
+    try {
+      didAuthenticate = await auth.authenticate(
+        localizedReason: prompt ?? 'Please authenticate with biometrics',
+        options: const AuthenticationOptions(
+          stickyAuth: true,
+          biometricOnly: true,
+        ),
+      );
+    } on PlatformException {
+      throw "Platform Exception : Biometrics Failed !";
+    }
+    if (!didAuthenticate) throw "Biometrics Failed";
+  }
+}

biometrics/lib/main.dart

@@ -0,0 +1,99 @@
+import 'package:biometrics/biometrics_verifier.dart';
+import 'package:flutter/material.dart';
+
+void main() => runApp(Biometrics());
+
+class Biometrics extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Biometrics',
+      theme: ThemeData(
+        appBarTheme: const AppBarTheme(elevation: 0),
+      ),
+      home: Home(),
+    );
+  }
+}
+
+class Home extends StatefulWidget {
+  @override
+  State<Home> createState() => _HomeState();
+}
+
+class _HomeState extends State<Home> {
+  late bool isVerified;
+
+  late BiometricsVerifier verifier;
+
+  @override
+  void initState() {
+    super.initState();
+    isVerified = false;
+    verifier = BiometricsVerifier();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: SizedBox(
+        width: double.infinity,
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Text(
+              isVerified ? 'Verification Complete' : 'Unverified',
+              style: const TextStyle(
+                fontSize: 16,
+                fontWeight: FontWeight.bold,
+              ),
+            ),
+            const SizedBox(height: 10),
+            isVerified
+                ? TextButton(
+                    onPressed: () {
+                      setState(() {
+                        isVerified = false;
+                      });
+                    },
+                    child: const Text('Unverify'),
+                  )
+                : TextButton(
+                    onPressed: () async {
+                      try {
+                        await verifier
+                            .verifyBiometrics('Please enter your fingerprint');
+                        // ---- Add your logic after finger print verification here
+                        // ---
+                        // ---
+                        setState(() {
+                          isVerified = true;
+                        });
+                      } catch (e) {
+                        // ---- Verification Failed
+                        showDialog(
+                          context: context,
+                          builder: (c) => AlertDialog(
+                            title: const Text('Error !'),
+                            content: Text(e.toString()),
+                            actions: [
+                              TextButton(
+                                onPressed: () {
+                                  Navigator.of(context).pop();
+                                },
+                                child: const Text('Ok'),
+                              )
+                            ],
+                          ),
+                        );
+                      }
+                    },
+                    child: const Text('Verify with Fingerprint'),
+                  ),
+          ],
+        ),
+      ),
+    );
+  }
+}