Swift Style

1---2name: swift-style3description: Swift code style conventions for clean, readable code. Use when writing Swift code to ensure consistent formatting, naming, organization, and idiomatic patterns.4---5 6# Swift Style Guide7 8Code style conventions for clean, readable Swift code.9 10## Core Principles11 12**Clarity > Brevity > Consistency**13 14Code should compile without warnings.15 16## Naming17 18- `UpperCamelCase` — Types, protocols19- `lowerCamelCase` — Everything else20- Clarity at call site21- No abbreviations except universal (URL, ID)22 23```swift24// Preferred25let maximumWidgetCount = 10026func fetchUser(byID id: String) -> User27```28 29## Golden Path30 31Left-hand margin is the happy path. Don't nest `if` statements.32 33```swift34// Preferred35func process(value: Int?) throws -> Result {36    guard let value = value else {37        throw ProcessError.nilValue38    }39    guard value > 0 else {40        throw ProcessError.invalidValue41    }42    return compute(value)43}44```45 46## Code Organization47 48Use extensions and MARK comments:49 50```swift51class MyViewController: UIViewController {52    // Core implementation53}54 55// MARK: - UITableViewDataSource56extension MyViewController: UITableViewDataSource { }57```58 59## Spacing60 61- Braces open on same line, close on new line62- One blank line between methods63- Colon: no space before, one space after64 65## Self66 67Avoid `self` unless required by compiler.68 69```swift70// Preferred71func configure() {72    backgroundColor = .systemBackground73}74```75 76## Computed Properties77 78Omit `get` for read-only:79 80```swift81var diameter: Double {82    radius * 283}84```85 86## Closures87 88Trailing closure only for single closure parameter.89 90## Type Inference91 92Let compiler infer when clear. For empty collections, use type annotation:93 94```swift95var names: [String] = []96```97 98## Syntactic Sugar99 100```swift101// Preferred102var items: [String]103var cache: [String: Int]104var name: String?105```106 107## Access Control108 109- `private` over `fileprivate`110- Don't add `internal` (it's the default)111- Access control as leading specifier112 113## Memory Management114 115```swift116resource.request().onComplete { [weak self] response in117    guard let self else { return }118    self.updateModel(response)119}120```121 122## Comments123 124- Explain **why**, not what125- Use `//` or `///`, avoid `/* */`126- Keep up-to-date or delete127 128## Constants129 130Use case-less enum for namespacing:131 132```swift133enum Math {134    static let pi = 3.14159135}136```137 138## Common Mistakes139 1401. **Abbreviations beyond URL, ID, UUID** — Abbreviations like `cfg`, `mgr`, `ctx`, `desc` hurt readability. Spell them out: `configuration`, `manager`, `context`, `description`. The three exceptions are URL, ID, UUID.141 1422. **Nested guard/if statements** — Deep nesting makes code hard to follow. Use early returns and guards to keep the happy path left-aligned.143 1443. **Inconsistent self usage** — Either always omit `self` (preferred) or always use it. Mixing makes code scanning harder and confuses capture semantics.145 1464. **Overly generic type names** — `Manager`, `Handler`, `Helper`, `Coordinator` are too vague. Names should explain responsibility: `PaymentProcessor`, `EventDispatcher`, `ImageCache`, `NavigationCoordinator`.147 1485. **Implied access control** — Don't skip access control. Explicit `private`, `public` helps future maintainers understand module boundaries. `internal` is default, so omit it.