How to handle a person permission warning?

Question

I wrote the following code snippet

if ([contextNew canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error])
{
    [contextNew evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:NSLocalizedString(@"",nil) reply:^(BOOL success, NSError *error)
    {
        if(success)
        {

        }
        else
        {

        }
    }
}

he appears in the sucess block after checking the face. I want to process a person permission notice. I want to get the yes method or the face identifier allowed for the person. Since we get something like AVAuthorizationStatus for the camera

Answer 1

Not sure if this will solve your problem or not, but I have the following options to detect the LAAuthenticationtype of error (in Swift you need to convert it to Objective-C)

laContext.evaluatePolicy(biometricsPolicy, localizedReason: localizedReason, reply: { (isSuccess, error) in
    if let laError = error {
       // handle error
       self.showLAError(laError: laError)
    } else if isSuccess {
      // handle success
    }
})


// function to detect an error type
func showLAError(laError: Error) -> Void {

    var message = ""

    switch laError {

    case LAError.appCancel:
        message = "Authentication was cancelled by application"

    case LAError.authenticationFailed:
        message = "The user failed to provide valid credentials"

    case LAError.invalidContext:
        message = "The context is invalid"

    case LAError.passcodeNotSet:
        message = "Passcode is not set on the device"

    case LAError.systemCancel:
        message = "Authentication was cancelled by the system"

    case LAError.touchIDLockout:
        message = "Too many failed attempts."

    case LAError.touchIDNotAvailable:
        message = "TouchID is not available on the device"

    case LAError.userCancel:
        message = "The user did cancel"

    case LAError.userFallback:
        message = "The user chose to use the fallback"

    default:

        if #available(iOS 11.0, *) {

            switch laError {

            case LAError.biometryNotAvailable:
                message = "Biometry is not available"

            case LAError.biometryNotEnrolled:
                message = "Authentication could not start, because biometry has no enrolled identities"

            case LAError.biometryLockout:
                message = "Biometry is locked. Use passcode."

            default:
                message = "Did not find error code on LAError object"
            }

        }
        message = "Did not find error code on LAError object"


    }

    //return message
    print("LAError message - \(message)")

}

Here is a list of all LAError types for Objective-C

Edit:

If you are trying to use Simulator, see here how to test Face-Id:

• Is it possible to check the face identifier in the simulator?

Objective-C. :

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

NSError *error;

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

    if (error != NULL) {
        // handle error
        //[self showError: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
            }
        }];
    }
}