ios native platform capabilities

I have outlined the implementation for LocalAuthentication using Face ID. This includes the mandatory privacy strings, the authentication manager, and the SwiftUI view integration.

Biometric Authentication Implementation

1. Info.plist Requirements

Add the following key to your Info.plist to prevent a crash on launch when requesting authentication:

• NSFaceIDUsageDescription: "We use Face ID to securely sign you into your account."

2. Authentication Manager

import LocalAuthentication
import Foundation

@Observable
class BiometricAuthManager {
    var isUnlocked = false
    var authError: String?

    func authenticate() {
        let context = LAContext()
        var error: NSError?

        // Check if biometric authentication is available
        if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            let reason = "Log in to your account"

            context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, authenticationError in
                DispatchQueue.main.async {
                    if success {
                        self.isUnlocked = true
                    } else {
                        self.authError = authenticationError?.localizedDescription ?? "Failed to authenticate"
                    }
                }
            }
        } else {
            // No biometrics available (e.g., not configured or hardware missing)
            self.authError = "Biometrics not available"
        }
    }
}

3. SwiftUI Integration

struct LoginView: View {
    @State private var authManager = BiometricAuthManager()

    var body: some View {
        VStack(spacing: 20) {
            if authManager.isUnlocked {
                Text("Access Granted")
                    .foregroundColor(.green)
            } else {
                Button("Unlock with Face ID") {
                    authManager.authenticate()
                }
                .buttonStyle(.borderedProminent)
            }

            if let error = authManager.authError {
                Text(error)
                    .font(.caption)
                    .foregroundColor(.red)
            }
        }
    }
}

Next steps

• Verify the NSFaceIDUsageDescription is localized if supporting multiple languages.
• Test the fallback path by denying permission in the iOS Settings app.
• Ensure the LAContext is not reused across different authentication attempts.