Touch ID vs Face ID code

Question

I wanted to ask a question about biometric authentication. In my app I entered authentication with Touch ID. Now voelvo implement the method with Face ID.

I inserted the line Privacy - Face ID Usage Description into my .plist file

Now I have noticed that my Face ID works correctly without making any changes to the TouchID code.

My question is :

** The Touch ID implementation code identical to that of the Face ID? Can I leave the Touch ID implementation code without making any changes or do I have to add a few lines of code for Face ID?**

I show you how I implemented my Touch ID

#pragma mark - TOUCH ID Login
-(void)useTouchID {
    NSError *error;
    LAContext *context = [[LAContext alloc] init];

    NSString *emailAccount = [KFKeychain loadObjectForKey:USER_EMAIL];
    NSString *reasonString = [NSString stringWithFormat:@"Autentica %@ utilizzando la tua impronta", emailAccount];

    if ([context canEvaluatePolicy:kLAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
        [context evaluatePolicy:kLAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason: reasonString reply:^(BOOL success, NSError * _Nullable error) {
            // Se la procedura con il TouchID va a buon fine settiamo il booleano su YES che specifica se l'utente a scelto di utilizzare il TouchID oppure NO.
            // Successivamente invochiamo il metodo loginWithFirebase per procedere con l'autenticazione su firebase

            dispatch_async(dispatch_get_main_queue(), ^{
                [APPDELEGATE showHud];
            });

            if (success) {
                _useBiometricsAuthentication = YES;
                // Attualmente il TouchID non viene supportato da Firebase pertanto dobbiamo autenticarci con l'impronta digitale e successivamente eseguire il login con Firebase.
                [self useFirebaseSignIn];
            }
            // Nel caso in cui si verifichino alcuni errori con l'uso del TouchID andiamo ad implementare ogni singolo errore che l'utente puo' riscontrare
            else {
                _useBiometricsAuthentication = NO;

                switch ([error code]) {
                        // L'autenticazione con Touch ID è fallità
                    case kLAErrorAuthenticationFailed:
                        NSLog(@"Autenticazione Fallita");
                        dispatch_async(dispatch_get_main_queue(), ^{
                            [APPDELEGATE removeHud];
                        });
                        break;
                        // L'user ha spinto annulla sull'alert che compare sulla richiesta di TouchID oppure ha spinto il pulsante Home facendo scomparire l'alert
                    case kLAErrorUserCancel:
                        NSLog(@"User ha respinto il touch ID");
                        dispatch_async(dispatch_get_main_queue(), ^{
                            [APPDELEGATE removeHud];
                        });
                        break;
                        // In questo caso l'user ha piu volte tentato di utilizzare il touchID e ha preferito inserire le proprie credenziali manualmente
                    case kLAErrorUserFallback:
                        NSLog(@"L'user ha scelto di utilizzare il login di firebase");
                        // a questo punto eliminiamo tutti i dati salvati con il login precedente in modo tale da poter salvare nuovamente le credenziali che l'utente ha inserito manualmente
                        [self deleteUserKey];
                        dispatch_async(dispatch_get_main_queue(), ^{
                            [APPDELEGATE removeHud];
                        });
                        break;
                        // L'errore ci comunica che l'utente molto probabilmente non ha mai inserito / salvato le proprie impronte digitali nel suo dispositivo
                    case kLAErrorTouchIDNotEnrolled:
                        NSLog(@" non sono state impostate impronte per utilizzare il touch id");
                        dispatch_async(dispatch_get_main_queue(), ^{
                            [APPDELEGATE showAlertWithTitle:@"ATTENZIONE" message:@"Il TUOCH ID ha bisogno di avere delle impronte digitali impostate per poter funzionare. Vai sulle IMPOSTAZIONI del tuo dispositivo in TOUCH ID e CODICE per inserirle" optionTitle:@"OK" otherOptionTitle:nil optionButtonAction:^{
                                [APPDELEGATE dismissAlert];
                            } canButtonAction:nil];
                            [APPDELEGATE removeHud];
                        });
                        break;
                        // In questo caso ci avverte che per utilizzare il TouchID l'app deve aver salvato almeno una volte le credenziali che l'utente inserisce manualmente, all'interno di un portachiavi come ad esempio la libreria utilizzata in questa app (Keychain)
                    case kLAErrorPasscodeNotSet: {
                        NSLog(@"il touch id ha bisogno di avere dei codici di accesso salvati per essere usato");
                        dispatch_async(dispatch_get_main_queue(), ^{
                            [APPDELEGATE showAlertWithTitle:@"ATTENZIONE" message:@"Sembra che non vi sia nessun account collegato a queste impronte. Perfavore effettua il login classico utilizzando la tua Email e la tua Password del tuo account Unistit e riprova." optionTitle:@"OK" otherOptionTitle:nil optionButtonAction:^{
                                [APPDELEGATE dismissAlert];
                                [self.emailField becomeFirstResponder];
                                [self deleteUserKey];
                            } canButtonAction:nil];
                            [APPDELEGATE removeHud];
                        });
                        break;
                    }
                    default:
                        break;
                }
            }
        }];
    }
}

Answer 1

You may be looking for this: biometryType is used to specify/update some localisables for user information only. Your working code will automatically identify biometryType and handle authentication operations. You don't need to update it.

Here is sample code, how you can manually detect, which biometry type is supported by device.

LAContext *laContext = [[LAContext alloc] init];

NSError *error;

if ([laContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {

    if (error != NULL) {
        // handle error
    } else {

        if (@available(iOS 11.0.1, *)) {
            if (laContext.biometryType == LABiometryTypeFaceID) {
                //localizedReason = "Unlock using Face ID"
                NSLog(@"FaceId support");
            } else if (laContext.biometryType == LABiometryTypeTouchID) {
                //localizedReason = "Unlock using Touch ID"
                NSLog(@"TouchId support");
            } else {
                //localizedReason = "Unlock using Application Passcode"
                NSLog(@"No Biometric support");
            }
        } else {
            // Fallback on earlier versions
        }


        [laContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:@"Test Reason" reply:^(BOOL success, NSError * _Nullable error) {

            if (error != NULL) {
                // handle error
            } else if (success) {
                // handle success response
            } else {
                // handle false response
            }
        }];
    }
}

Answer 2

You don't have to update your code to be Face ID ready if your app already supports Touch ID. (as seen here ) iOS takes care of all the work under the hood.

What you can do however, is to change your strings containing "Touch ID" to "Face ID" if the app is running on a Face ID capable device.

Edit: As noted by MikeMertsock , the LAContext class has a biometryType property to determine whether the device uses Touch ID or Face ID.

Answer 3

 func authenticateUser() {
        // Get the local authentication context.
        let context = LAContext()

        // Declare a NSError variable.

        // Set the reason string that will appear on the authentication alert.
        _ = "Authentication is needed to access your notes."

        var policy: LAPolicy?
        // Depending the iOS version we'll need to choose the policy we are able to use
        if #available(iOS 9.0, *) {
            // iOS 9+ users with Biometric and Passcode verification
            policy = .deviceOwnerAuthentication
        } else {
            // iOS 8+ users with Biometric and Custom (Fallback button) verification
            context.localizedFallbackTitle = "Fuu!"
            policy = .deviceOwnerAuthenticationWithBiometrics
        }

        context.evaluatePolicy(policy!, localizedReason: "Please Add your touch Id", reply: { (success, error) in



            DispatchQueue.main.async {
              RKDropdownAlert.title(NSLocalizedString("Success", comment: ""), message: NSLocalizedString("User Touch Id Enrolled Successfully", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)

                guard success else {


                    guard let error = error else {
                        return
                    }


                    switch(error) {
                    case LAError.authenticationFailed:
                        //self.message.text = "There was a problem verifying your identity."
                        break
                    case LAError.userCancel:

                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("User cancelled", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)

                       // self.message.text = "Authentication was canceled by user."
                        // Fallback button was pressed and an extra login step should be implemented for iOS 8 users.
                    // By the other hand, iOS 9+ users will use the pasccode verification implemented by the own system.
                        break
                    case LAError.userFallback:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("The user tapped the fallback", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
                        //self.message.text = "The user tapped the fallback button (Fuu!)"
                        break
                    case LAError.systemCancel:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("Authentication was canceled by system", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Authentication was canceled by system."
                        break
                    case LAError.passcodeNotSet:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("Passcode is not set on the device", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Passcode is not set on the device."
                        break
                    case LAError.touchIDNotAvailable:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("Touch ID is not available on the device", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Touch ID is not available on the device."
                        break
                    case LAError.touchIDNotEnrolled:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("TTouch ID has no enrolled fingers", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Touch ID has no enrolled fingers."
                        break
                    // iOS 9+ functions
                    case LAError.touchIDLockout:
                         RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("here were too many failed Touch ID attempts and Touch ID is now locked", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
                        break
                    case LAError.appCancel:
                         RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("Authentication was canceled by application", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Authentication was canceled by application."
                        break
                    case LAError.invalidContext:
                         RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("LAContext passed to this call has been previously invalidated.", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "LAContext passed to this call has been previously invalidated."
                        break
                    default:
                        RKDropdownAlert.title(NSLocalizedString("Error", comment: ""), message: NSLocalizedString("Touch ID may not be configured", comment: ""), backgroundColor: BMConstants.KAppBGColor, textColor: BMConstants.KAppWhiteColor)
//                        self.message.text = "Touch ID may not be configured"

                        break
                    }


                    return
                }

            }
        }



        )



           }