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Swift Academy · Lesson

Result<Success, Failure> Fundamentals

Creating and pattern-matching Result values for explicit error handling.

Result<Success, Failure> Fundamentals is a free Swift Academy lesson on CoddyKit — lesson 1 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

`Result` is a Swift enum with two cases — `.success` and `.failure` — providing explicit error handling without throws/catch syntax.

Declaring Result

```swift func divide(_ a: Double, by b: Double) -> Result { guard b != 0 else { return .failure(.divisionByZero) } return .success(a / b) } enum DivisionError: Error { case divisionByZero } ```

Consuming Result

```swift switch divide(10, by: 2) { case .success(let value): print("Result: \(value)") case .failure(let err): print("Error: \(err)") } ```

get() — Throws on Failure

```swift let result = divide(10, by: 0) do { let value = try result.get() // throws DivisionError } catch { print(error) } ```

Storing Results

```swift var cache: [URL: Result] = [:] cache[url] = .success(data) cache[url] = .failure(URLError(.notConnectedToInternet)) ```

Result in Async APIs

```swift func fetch(url: URL, completion: @escaping (Result) -> Void) { URLSession.shared.dataTask(with: url) { data, _, error in if let data { completion(.success(data)) } else { completion(.failure(error ?? URLError(.unknown))) } }.resume() } ```

Pattern Matching with if case

```swift if case .success(let data) = result { process(data) } if case .failure(let err) = result { handle(err) } ```

Success and Failure Properties

```swift let r: Result = .success(42) print(r.success) // Optional(42) — non-nil on success print(r.failure) // nil ```

Initialising from Throws

```swift let result = Result { try JSONDecoder().decode(User.self, from: data) } // .success(user) or .failure(decodingError) ```

Comparing Results

```swift let a: Result = .success(42) let b: Result = .success(42) // Cannot == directly unless Success/Failure are Equatable ```

Quick Check

What does `result.get()` do when the Result is `.failure`?

Recap

Key takeaways: • `Result` — explicit success/failure without throws • `.success(value)` / `.failure(error)` — two cases • `.get()` throws on failure • `Result { try ... }` bridges throwing code • Useful for storing/passing deferred results Next: map and flatMap on Result.

Frequently asked questions

Is the “Result<Success, Failure> Fundamentals” lesson free?

Yes — the full text of “Result<Success, Failure> Fundamentals” 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 “Result<Success, Failure> Fundamentals”?

Creating and pattern-matching Result values for explicit error handling. 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 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Result<Success, Failure> Fundamentals” 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. Result Fundamentals
  2. map and flatMap on Result
  3. Custom Error Types with LocalizedError
  4. Bridging Result to async/await
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