BiometricAuth

BiometricAuth.swift

import LocalAuthentication

class BiometricAuth {
    
    var context = LAContext()
    var error: NSError?
    
    
    func auth(_ completion: @escaping (_ success: Bool) -> ()) {
        // Get the supported biometry
        var biometry = context.biometryType
        
        // Check for biometric authentication
        // permissions
        var permissions = context.canEvaluatePolicy(
            .deviceOwnerAuthentication,
            error: &error
        )
        
        if permissions {
            let reason = "Log in with Face ID"
            context.evaluatePolicy(
                // .deviceOwnerAuthentication allows
                // biometric or passcode authentication
                .deviceOwnerAuthentication,
                localizedReason: reason
            ) { success, error in
                if success {
                    // Handle successful authentication
                } else {
                    self.error = error as? NSError
                    self.handleErrors()
                }
                completion(success)
            }
        } else {
            // Handle permission denied or error
        }
        
    }
    
    func handleErrors() {
        // If error is an instance of LAError
        var code = LAError.Code(rawValue: error!.code)
        
        switch code {
        case .appCancel:
            break
            // The app canceled authentication by
            // invalidating the LAContext
        case .authenticationFailed:
            break
            // The user did not provide
            // valid credentials
        case .invalidContext:
            break
            // The LAContext was invalid
        case .notInteractive:
            break
            // Interaction was not allowed so the
            // authentication failed
        case .passcodeNotSet:
            break
            // The user has not set a passcode
            // on this device
        case .systemCancel:
            break
            // The system canceled authentication,
            // for example to show another app
        case .userCancel:
            break
            // The user canceled the
            // authentication dialog
        case .userFallback:
            break
            // The user selected to use a fallback
            // authentication method
        case .biometryLockout:
            break
            // Too many failed attempts locked
            // biometric authentication
        case .biometryNotAvailable:
            break
            // The user's device does not support
            // biometric authentication
        case .biometryNotEnrolled:
            break
            // The user has not configured
            // biometric authentication
        @unknown default:
            break
            // An other error occurred
        }
    }
}