如何修复线程或处理Swift中的错误？

enum NetworkError: Error {
    case invalidURL
    case requestFailed
}

func fetchData(from urlString: String) throws -> Data {
    guard let url = URL(string: urlString) else {
        throw NetworkError.invalidURL
    }
    
    let (data, response) = try await URLSession.shared.data(from: url)
    
    guard let httpResponse = response as? HTTPURLResponse,
          (200...299).contains(httpResponse.statusCode) else {
        throw NetworkError.requestFailed
    }
    
    return data
}

do {
    let data = try fetchData(from: "https://api.example.com/data")
    print("Data fetched successfully: \(data)")
} catch NetworkError.invalidURL {
    print("The provided URL is invalid.")
} catch NetworkError.requestFailed {
    print("The request failed.")
} catch {
    print("An unexpected error occurred: \(error).")
}

import Foundation

func performTask(completion: @escaping (Result<String, Error>) -> Void) {
    DispatchQueue.global().async {
        // Simulate a long-running task
        sleep(2)
        
        // Upon completion, call the completion handler with result or error
        completion(.success("Task completed successfully"))
        // If there was an error:
        // completion(.failure(SomeError()))
    }
}

performTask { result in
    switch result {
    case .success(let message):
        print(message)
    case .failure(let error):
        print("An error occurred: \(error).")
    }
}

DispatchQueue.global().async {
    // Perform long-running task
    DispatchQueue.main.async {
        // Update UI on the main thread
    }
}