Handling Offline Scenarios

Mobile apps must gracefully handle offline scenarios while maintaining security.

// iOS - Secure offline data synchronization
class OfflineDataManager {
    
    private let syncQueue = DispatchQueue(label: "com.app.sync", qos: .background)
    private let reachability = try! Reachability()
    
    init() {
        setupReachabilityObserver()
    }
    
    // Queue secure operations for offline execution
    func queueSecureOperation(_ operation: SecureOperation) {
        let encryptedOp = encryptOperation(operation)
        
        // Store in secure local database
        CoreDataManager.shared.save(encryptedOp)
        
        // Attempt sync if online
        if reachability.connection != .unavailable {
            syncPendingOperations()
        }
    }
    
    private func syncPendingOperations() {
        syncQueue.async { [weak self] in
            guard let self = self else { return }
            
            let pendingOps = CoreDataManager.shared.fetchPendingOperations()
            
            for encryptedOp in pendingOps {
                guard let operation = self.decryptOperation(encryptedOp) else {
                    continue
                }
                
                // Validate operation is still valid
                if !self.isOperationExpired(operation) {
                    self.executeSecureOperation(operation) { success in
                        if success {
                            CoreDataManager.shared.markAsSync(encryptedOp)
                        }
                    }
                } else {
                    // Remove expired operations
                    CoreDataManager.shared.delete(encryptedOp)
                }
            }
        }
    }
    
    private func isOperationExpired(_ operation: SecureOperation) -> Bool {
        let expirationTime = operation.timestamp.addingTimeInterval(24 * 60 * 60) // 24 hours
        return Date() > expirationTime
    }
}

struct SecureOperation: Codable {
    let id: String
    let type: OperationType
    let payload: Data
    let timestamp: Date
    let signature: String
}

Network security and API protection are critical components of mobile application security. By implementing proper transport layer security, certificate pinning, API authentication, and abuse prevention measures, developers can protect their applications from network-based attacks. Remember that security is not a one-time implementation but an ongoing process that requires regular updates and monitoring. The next chapter explores authentication and authorization mechanisms to ensure only legitimate users can access your application's features.## Authentication and Authorization

Authentication and authorization form the cornerstone of mobile application security, determining who can access your app and what they can do within it. This chapter explores modern authentication methods, from traditional passwords to biometric authentication and passwordless solutions. We'll examine how to implement robust authorization systems that protect resources while providing seamless user experiences across iOS and Android platforms.