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Swift Academy · Lesson

Networking with Combine and URLSession

Using URLSession.dataTaskPublisher with Combine to handle network responses.

Networking with Combine and URLSession is a free Swift Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Swift Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Welcome

URLSession has built-in Combine support via `dataTaskPublisher`. Combined with `decode`, it makes type-safe networking pipelines in just a few lines.

dataTaskPublisher

```swift URLSession.shared .dataTaskPublisher(for: URL(string:"https://api.example.com/users")!) .sink(receiveCompletion: { print($0) }, receiveValue: { data, response in print(data.count) }) .store(in: &cancellables) ```

Decoding JSON

```swift struct User: Decodable { var name: String; var id: Int } URLSession.shared .dataTaskPublisher(for: url) .map(\.data) .decode(type: [User].self, decoder: JSONDecoder()) .receive(on: DispatchQueue.main) .sink(receiveCompletion: { print($0) }, receiveValue: { users in self.users = users }) .store(in: &cancellables) ```

Error Handling with catch

```swift .catch { error -> AnyPublisher<[User],Never> in print("Error: \(error)") return Just([]).eraseToAnyPublisher() } ```

retry

```swift .retry(3) // retry up to 3 times on failure ```

Validating HTTP Status

```swift .tryMap { data, response -> Data in guard let http = response as? HTTPURLResponse, (200...299).contains(http.statusCode) else { throw URLError(.badServerResponse) } return data } ```

Building a Generic Publisher

```swift func fetch(_ url: URL) -> AnyPublisher { URLSession.shared.dataTaskPublisher(for: url) .map(\.data) .decode(type: T.self, decoder: JSONDecoder()) .eraseToAnyPublisher() } ```

Cancellation

```swift var searchCancellable: AnyCancellable? searchCancellable?.cancel() // cancel previous searchCancellable = fetch(url).sink { ... } ```

flatMap for Sequential Requests

```swift fetch(userUrl) .flatMap { user in fetch(user.profileUrl) } .sink { profile in render(profile) } .store(in: &cancellables) ```

Combining Multiple Requests

```swift Publishers.Zip(fetch(url1), fetch(url2)) .sink { a, b in combinedUI(a, b) } .store(in: &cancellables) ```

Quick Check

Which Combine operator decodes publisher output into a Decodable type?

Recap

Key takeaways: • `dataTaskPublisher(for:)` — Combine-based URL fetching • `.map(\.data)` → `.decode(type:decoder:)` for JSON • `.tryMap` validates HTTP status • `.retry(n)` for automatic retries • `.catch { }` provides a fallback publisher Course complete! Next: Swift Structured Concurrency.

Frequently asked questions

Is the “Networking with Combine and URLSession” lesson free?

Yes — the full text of “Networking with Combine and URLSession” is free to read here on the web, and the Swift Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Swift Academy course, upgrade to CoddyKit PRO.

What will I learn in “Networking with Combine and URLSession”?

Using URLSession.dataTaskPublisher with Combine to handle network responses. You practise Swift Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Swift Academy?

No prior experience is required. Swift Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Networking with Combine and URLSession” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Swift Academy lesson?

Yes. Every Swift Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Publishers and Subscribers
  2. Operators: map, filter, combineLatest
  3. PassthroughSubject and CurrentValueSubject
  4. Networking with Combine and URLSession
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