Swift Coding Style

This file extends common/coding-style.md with Swift specific content.

Formatting

• SwiftFormat for auto-formatting, SwiftLint for style enforcement
• swift-format is bundled with Xcode 16+ as an alternative

Immutability

• Prefer let over var — define everything as let and only change to var if the compiler requires it
• Use struct with value semantics by default; use class only when identity or reference semantics are needed

Naming

Follow Apple API Design Guidelines:

• Clarity at the point of use — omit needless words
• Name methods and properties for their roles, not their types
• Use static let for constants over global constants

Error Handling

Use typed throws (Swift 6+) and pattern matching:

func load(id: String) throws(LoadError) -> Item {
    guard let data = try? read(from: path) else {
        throw .fileNotFound(id)
    }
    return try decode(data)
}

Concurrency

Enable Swift 6 strict concurrency checking. Prefer:

• Sendable value types for data crossing isolation boundaries
• Actors for shared mutable state
• Structured concurrency (async let, TaskGroup) over unstructured Task {}