API reference

Everything is exported by:

import 'package:flutter_local_authentication/flutter_local_authentication.dart';
import 'package:flutter_local_authentication/localization_model.dart'; // LocalizationModel

The generated dartdoc has the same information with links to the source.

FlutterLocalAuthentication

The entry point of the plugin. It has a default constructor with no parameters.

final auth = FlutterLocalAuthentication();

canAuthenticate

Future<bool> canAuthenticate({
  AuthenticationMethod method = AuthenticationMethod.biometricsOnly,
})

Checks if the user can authenticate with method on this device.

Returns true when the platform supports the method and everything it needs is set up (hardware, enrolled biometrics, a device credential). Returns false otherwise, including when the platform does not support the method. It never shows any UI.

authenticate

Future<bool> authenticate({
  AuthenticationMethod method = AuthenticationMethod.biometricsOnly,
})

Shows the native prompt and completes when the user is done with it.

• Returns true when the user is authenticated.
• Throws an AuthenticationException in every other case. Its reason tells what happened.

It never returns false.

getAvailability

Future<AuthenticationAvailability> getAvailability({
  AuthenticationMethod method = AuthenticationMethod.biometricsOnly,
})

The detailed version of canAuthenticate: tells whether the user can authenticate with method, and the reason why when they can not. It never shows any UI. See availability.

getBiometryType

Future<BiometryType> getBiometryType()

Returns the kind of biometrics of the device, to label your UI. It tells what the device has, not what the user enrolled.

cancelAuthentication

Future<bool> cancelAuthentication()

Dismisses the prompt that is being shown. The pending authenticate call throws an AuthenticationException with the reason systemCanceled. Returns true if there was a prompt to dismiss. Not supported on Linux, where it returns false. See dismissing the prompt.

setLocalizationModel

Future<void> setLocalizationModel(LocalizationModel localizationModel)

Sets the texts of the following prompts. Applies to Android, iOS, macOS and Windows, and does nothing on Linux. The returned future completes when the platform has stored the model. See localization.

setTouchIDAuthenticationAllowableReuseDuration

Future<double> setTouchIDAuthenticationAllowableReuseDuration(double duration)

iOS and macOS. Sets for how many seconds after a Touch ID device unlock the user is authenticated without a prompt. Returns the stored value, which the system caps at 5 minutes. On other platforms it returns duration and does nothing. See Touch ID reuse duration.

getTouchIDAuthenticationAllowableReuseDuration

Future<double> getTouchIDAuthenticationAllowableReuseDuration()

iOS and macOS. Returns the current allowable reuse duration, in seconds. On other platforms it returns 0.

AuthenticationMethod

enum AuthenticationMethod {
  biometricsOnly,
  biometricsOrDeviceCredential,
  deviceCredentialOnly,
}

Value	Description	Supported on
biometricsOnly	Biometrics only. The default.	Android, iOS, macOS, Linux
biometricsOrDeviceCredential	Biometrics, falling back to the PIN, pattern, passcode or password.	Android, iOS, macOS
deviceCredentialOnly	PIN, pattern, passcode or password only.	Android 11 (API 30) or newer, iOS, macOS

See authentication methods.

AuthenticationAvailability

enum AuthenticationAvailability {
  available,
  notAvailable,
  notEnrolled,
  lockedOut,
  credentialNotSet,
  unsupportedMethod,
}

Returned by getAvailability. Each value is described in availability.

BiometryType

enum BiometryType { none, fingerprint, face, iris, multiple }

Returned by getBiometryType. Each value is described in labeling your UI.

AuthenticationException

class AuthenticationException extends PlatformException

Thrown by authenticate when the user is not authenticated.

Member	Description
reason	An AuthenticationErrorReason: what happened, on every platform.
isCanceled	true when the reason is userCanceled or systemCanceled.
code	authentication_error (AuthenticationException.authenticationErrorCode) or unsupported_method.
message	The platform's localized description of the error.
details	The raw information of the platform: reason, native errorCode and message.

AuthenticationErrorReason

enum AuthenticationErrorReason {
  userCanceled,
  systemCanceled,
  lockedOut,
  notEnrolled,
  notAvailable,
  credentialNotSet,
  unsupportedMethod,
  failed,
}

Each value is described in error handling.

unsupportedAuthenticationMethodErrorCode

const String unsupportedAuthenticationMethodErrorCode = 'unsupported_method';

The code of the AuthenticationException thrown by authenticate when the platform does not support the requested method. Its reason is unsupportedMethod.

LocalizationModel

LocalizationModel({
  required String promptDialogTitle,
  required String promptDialogReason,
  required String cancelButtonTitle,
})

Member	Description
promptDialogTitle	Title of the prompt (Android).
promptDialogReason	Why the app asks the user to authenticate.
cancelButtonTitle	Title of the button that cancels the prompt.
LocalizationModel.fromJson()	Creates a model from a Map<String, dynamic>.
toJson()	Converts the model to a Map<String, dynamic>.

Platform interface

FlutterLocalAuthenticationPlatform and MethodChannelFlutterLocalAuthentication are the plugin's platform interface. Apps do not use them directly. They are useful to mock the plugin in tests:

class FakeLocalAuthentication extends FlutterLocalAuthenticationPlatform
    with MockPlatformInterfaceMixin {
  @override
  Future<bool> canAuthenticate({
    AuthenticationMethod method = AuthenticationMethod.biometricsOnly,
  }) async => true;

  @override
  Future<bool> authenticate({
    AuthenticationMethod method = AuthenticationMethod.biometricsOnly,
  }) async => true;
}

void main() {
  setUp(() {
    FlutterLocalAuthenticationPlatform.instance = FakeLocalAuthentication();
  });
}