What are error handling patterns for UIKit in Swift?

// Swift error handling in UIKit example

import UIKit

enum DataError: Error {
    case dataNotFound
    case networkError(String)
}

func fetchData(completion: @escaping (Result) -> Void) {
    let dataFound = false // Simulate a data fetch
    if dataFound {
        // Simulating successful data retrieval
        let data = Data() // Replace with actual data
        completion(.success(data))
    } else {
        // Simulating an error
        completion(.failure(.dataNotFound))
    }
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        fetchData { result in
            switch result {
            case .success(let data):
                print("Data fetched successfully: \(data)")
            case .failure(let error):
                self.handleError(error)
            }
        }
    }

    func handleError(_ error: DataError) {
        switch error {
        case .dataNotFound:
            print("Error: Data not found.")
            // Display an alert to the user
        case .networkError(let message):
            print("Network error: \(message)")
            // Display an alert to the user
        }
    }
}