{
    "api": "YAML JSON TOON Database",
    "version": "1.0.0",
    "format": "json",
    "dataset": {
        "id": 51,
        "slug": "swift-language-features",
        "title": "Swift Language Features",
        "description": "Swift programming language features: optionals, protocol-oriented programming, generics, async/await, SwiftUI, and memory management (ARC).",
        "summary": "Swift language features with the version they arrived, a description, syntax and notes: optionals, protocol-oriented programming, generics, result builders, async/await, actors, property wrappers and automatic reference counting.",
        "use_when": [
            "You are learning Swift or reading SwiftUI-era code.",
            "You need the Swift version in which a feature appeared."
        ],
        "caveats": [
            "Swift evolves quickly; confirm feature availability against the Xcode and Swift version you target.",
            "Strict concurrency checking has been rolled out in stages and can change build behavior."
        ],
        "related": [
            "language-comparison-2026",
            "csharp-dotnet-features",
            "rust-language-features",
            "behavioral-design-patterns"
        ],
        "category": "Programming Languages",
        "category_slug": "programming-languages",
        "tags": "swift,ios,optionals,protocols,generics,async-await,swiftui,arc",
        "view_count": 0,
        "created_at": 1778695229,
        "updated_at": 1778695229,
        "entry_count": 8,
        "fields": [
            {
                "section": "features",
                "field": "name",
                "type": "string",
                "example": "Optionals"
            },
            {
                "section": "features",
                "field": "introduced",
                "type": "string",
                "example": "Swift 1.0"
            },
            {
                "section": "features",
                "field": "description",
                "type": "string",
                "example": "Type-safe way to represent nil values: Optional…"
            },
            {
                "section": "features",
                "field": "syntax",
                "type": "string",
                "example": "var name: String?; if let unwrapped = name { }"
            },
            {
                "section": "features",
                "field": "notes",
                "type": "string",
                "example": "Force unwrap (!) crashes on nil; use guard let …"
            }
        ]
    },
    "data": {
        "features": [
            {
                "name": "Optionals",
                "introduced": "Swift 1.0",
                "description": "Type-safe way to represent nil values: Optional<T> enum with .none and .some(T)",
                "syntax": "var name: String?; if let unwrapped = name { }",
                "notes": "Force unwrap (!) crashes on nil; use guard let for early exit"
            },
            {
                "name": "Protocol-Oriented Programming",
                "introduced": "Swift 2.0",
                "description": "Define behavior via protocols with default implementations in extensions",
                "syntax": "protocol Drawable { func draw() }; extension Drawable { func draw() { /* default */ } }",
                "notes": "Prefer protocols over inheritance for flexibility and composition"
            },
            {
                "name": "Generics",
                "introduced": "Swift 1.0",
                "description": "Write flexible, reusable code with type parameters and constraints",
                "syntax": "func swap<T>(_ a: inout T, _ b: inout T) { (a, b) = (b, a) }",
                "notes": "Use where clauses for complex constraints: func process<T: Equatable>(items: [T]) where T: Hashable"
            },
            {
                "name": "Result Builder",
                "introduced": "Swift 5.4",
                "description": "DSL-like syntax for building values ( SwiftUI views, async let groups)",
                "syntax": "@resultBuilder struct HTMLBuilder { static func buildBlock(_ parts: String...) -> String { parts.joined() } }",
                "notes": "Foundation of SwiftUI's declarative syntax"
            },
            {
                "name": "async/await",
                "introduced": "Swift 5.5",
                "description": "Structured concurrency with async functions, await keyword, and structured task groups",
                "syntax": "async func fetchData() async throws -> Data { try await URLSession.shared.data(from: url) }",
                "notes": "Replaces callback-based patterns; integrates with actors for thread safety"
            },
            {
                "name": "Actors",
                "introduced": "Swift 5.5",
                "description": "Reference types with actor isolation: only one task accesses mutable state at a time",
                "syntax": "actor BankAccount { var balance: Double; func deposit(_ amount: Double) async { balance += amount } }",
                "notes": "Prevents data races; await required when accessing from outside"
            },
            {
                "name": "Property Wrappers",
                "introduced": "Swift 5.1",
                "description": "Separate property storage logic from definition: @propertyWrapper struct",
                "syntax": "@propertyWrapper struct Lazy<T> { var value: T?; var wrappedValue: T { get set } }",
                "notes": "Used by @State, @Binding, @ObservedObject in SwiftUI"
            },
            {
                "name": "ARC (Automatic Reference Counting)",
                "introduced": "Swift 1.0",
                "description": "Memory management via reference counting; weak/unowned for breaking retain cycles",
                "syntax": "weak var delegate: DelegateProtocol?; unowned let owner: Owner",
                "notes": "No garbage collector; understand strong/weak/unowned to avoid leaks and crashes"
            }
        ]
    }
}