Ios Security

Here’s a quick-start iOS security example that covers secure token storage, biometric unlock, and protected file writes:

```swift
import Foundation
import LocalAuthentication
import Security

enum SecureStore {
    static func saveToken(_ token: String, account: String = "authToken") throws {
        let data = Data(token.utf8)
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrAccount as String: account,
            kSecValueData as String: data
        ]

        SecItemDelete(query as CFDictionary)
        let status = SecItemAdd(query as CFDictionary, nil)
        guard status == errSecSuccess else {
            throw NSError(domain: NSOSStatusErrorDomain, code: Int(status))
        }
    }

    static func readToken(account: String = "authToken") throws -> String {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrAccount as String: account,
            kSecReturnData as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne
        ]

        var item: CFTypeRef?
        let status = SecItemCopyMatching(query as CFDictionary, &item)
        guard status == errSecSuccess,
              let data = item as? Data,
              let token = String(data: data, encoding: .utf8) else {
            throw NSError(domain: NSOSStatusErrorDomain, code: Int(status))
        }

        return token
    }
}

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

    guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {
        completion(false)
        return
    }

    context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics,
                           localizedReason: "Unlock your secure session") { success, authError in
        if let laError = authError as? LAError {
            switch laError.code {
            case .userCancel, .authenticationFailed:
                completion(false)
            default:
                completion(false)
            }
            return
        }
        completion(success)
    }
}

func saveProtectedFile(_ data: Data, to url: URL) throws {
    try data.write(to: url, options: .completeFileProtection)
}
```

Use this as the baseline:

- Store tokens and PII in Keychain with `SecItemAdd` / `SecItemCopyMatching`, not `UserDefaults`
- Gate sensitive actions with `LAContext` and check `canEvaluatePolicy` first
- Write sensitive files with `.completeFileProtection`
- Keep App Transport Security enabled
- Avoid logging tokens or PII in release builds
- Add certificate pinning for production network traffic