EducaSwift

In any Swift architecture, the concept of a "Service" plays a crucial role. Services are essential for managing external data, handling networking tasks, and organizing code in a way that maintains a clean separation of concerns. In this article, we’ll explore what a service is, how it fits into different architecture, and a basic implementation of a service in Swift.

A service may handle:

• Fetching data from a remote API
• Saving data to a local database
• Processing and transforming data before sending it to the ViewModel

Benefits of Using Services

Incorporating services into your architecture provides several benefits:

• Modularity: Services keep your code organized by isolating network and data operations into separate, reusable components.
• Testability: By isolating data-fetching logic in services, you can test data handling independently from the rest of the app.
• Reusability: Services can be reused across multiple ViewModels, making them efficient and reducing code duplication.

Creating a service

Let's see an example where a ProductService provides a function to fetch a list of products. As you can see this service will manage the connection with the server and will provide a final result, so wherever you use this service, you only need to worry about calling fetchProduct function.

import Foundation

enum ProductServiceError: Error {
    case wrongUrl
    case networkError
}

class ProductService {

    func fetchProducts() async throws -> [Product] {
        guard let url = URL(string: "https://educaswift.com/public/products.json") else {
            throw ProductServiceError.wrongUrl
        }

        do {
            let urlRequest = try URLRequest(url: url, method: .post)

            let (data, _) = try await URLSession.shared.data(for: urlRequest)

            let products = try JSONDecoder().decode([Product].self, from: data)

            return products
        }
        catch {
            throw ProductServiceError.networkError
        }
    }
}

We could add more function to our service like addProduct, removeProduct, fetchProductDetail, always related with the purpose of the service, in this case, managing products.

ServiceError

A Service handles data from various sources, such as network requests, databases, or other systems. To streamline error handling, we've created a unified error type, ProductServiceError, so that our Service returns a consistent error type across all operations.

Using our Service

As we mentioned earlier, a Service is usefull in any architecture, but for this example let's see how it would work in a ViewModel.

@Observable
class ViewModel {

    var products: [Product] = []

    let productService: ProductService = ProductService()

    func onAppear() {
        Task {
            await fetchProducts()
        }
    }

    func fetchProducts() async {
        do {
            products = try await productService.fetchProducts()
        }
        catch {
            // Handle errors here
        }
    }
}

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