How to Implement Face Authentication for App Unlocking Programmatically

How can I implement face authentication to unlock my app programmatically?

// Example code snippet for face authentication verification using Face ID in Swift
import LocalAuthentication

func authenticateUser(completion: @escaping (Bool) -> Void) {
    let context = LAContext()
    var error: NSError?

    if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
        let reason = "Please authenticate yourself to unlock the app"

        context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, authenticationError in
            DispatchQueue.main.async {
                completion(success)
            }
        }
    } else {
        // Handle the error if biometric authentication is not available
        completion(false)
    }
}

Implementing face authentication allows your application to securely access features after user verification. This involves leveraging platform-specific biometric authentication capabilities, which provides a seamless and secure experience.

// Swift function to unlock app with Face ID
authenticateUser { success in
    if success {
        print("Authentication successful, unlocking app.")
    } else {
        print("Authentication failed, please try again.")
    }
}

Causes

• The app does not support biometric authentication.
• User has not set up face recognition on their device.
• Biometrics are disabled in the device settings.

Solutions

• Ensure that your app has permission to access biometric hardware.
• Implement fallback authentication methods (such as a PIN) for users without biometric setup.
• Test on real devices to verify functionality and handle different biometric types.

Mistake: Forgetting to handle cases where biometric authentication is not available.

Solution: Implement proper error handling and provide alternate authentication methods.

Mistake: Hardcoding error messages instead of localizing them.

Solution: Use localization for all user-facing text to support multiple languages.