How do you make HTTP requests in a mobile application? What are the common methods for consuming a REST API?

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Accepted Answer

Making HTTP requests to consume REST APIs is one of the most fundamental tasks in mobile development. Nearly every app needs to communicate with a backend server to fetch data, submit forms, authenticate users, or synchronize content.

In React Native, the most common approach is using the fetch API, which is built into the JavaScript runtime. Fetch is a promise-based API that sends a request and returns a response. A basic GET request looks like fetch('https://api.example.com/users'), which returns a promise that resolves to a Response object. You then call response.json() to parse the JSON body. For POST requests, you pass a second argument with the method, headers including Content-Type set to application/json, and a stringified body.

Axios is a popular alternative to fetch in React Native. It provides a more feature-rich API with automatic JSON parsing, request and response interceptors for adding authentication headers or handling errors globally, request cancellation, and timeout configuration. Many teams prefer Axios because it reduces boilerplate. For example, you can create an Axios instance with a base URL and default headers, then use instance.get('/users') or instance.post('/users', data) for all requests.

In Flutter, the http package provides basic HTTP functionality similar to fetch. You import the package, then use http.get(Uri.parse('https://api.example.com/users')) for GET requests. The Dio package is Flutter's equivalent of Axios, offering interceptors, file uploading, request cancellation, and automatic JSON serialization. Dio is the more common choice for production Flutter apps due to its richer feature set.

For native iOS, URLSession is the standard networking API. You create a URL, build a URLRequest, and use URLSession.shared.dataTask to execute it. Modern Swift code uses async/await with URLSession for cleaner asynchronous code. Alamofire is the most popular third-party networking library for iOS, providing a more ergonomic API.

For native Android, OkHttp is the standard HTTP client, and Retrofit builds on top of it to provide a type-safe REST client. Retrofit lets you define your API as an interface with annotated methods, and it generates the implementation automatically.

Regardless of the tool you choose, several practices apply universally. Always make network requests asynchronously to avoid blocking the UI thread. Handle errors gracefully by catching network failures, timeouts, and server errors. Parse response status codes to differentiate between success (200-299), client errors (400-499), and server errors (500-599). Use a centralized API client rather than scattering fetch calls throughout your codebase, which makes it easier to add authentication headers, handle token refresh, and implement consistent error handling.