Swift

Swift is Apple’s modern, type-safe language for iOS, macOS, watchOS, tvOS, and server apps.

Keywords

• associatedtype, class, deinit, enum, extension, func, import, init, infix, let, operator, postfix, prefix, protocol, static, struct, subscript, typealias, var.
• Control flow: break, case, continue, default, defer, do, else, fallthrough, for, guard, if, in, repeat, return, switch, throw, throws, try, where, while.
• Access control: open, public, internal, fileprivate, private.
• Concurrency: async, await, actor, nonisolated, isolated.

Language Features

• Protocol-oriented programming with protocol extensions.
• Value semantics through structs and enums; classes for reference semantics.
• Optionals (`String?`) eliminate null pointer crashes.
• Pattern matching with `switch`, `if case`, `guard case`.
• Result builders power DSLs like SwiftUI.
• Async/await and actors (Swift 5.5+) simplify concurrency.

Standard Library & Frameworks

• Foundation adds dates, networking, localization.
• SwiftUI and UIKit/AppKit for UI development.
• Combine handles reactive streams; SwiftData and CoreData persist models.
• Server stacks: Vapor, Kitura, Hummingbird, AsyncHTTPClient.

Operators

• Arithmetic: + - * / %
• Comparison: == != < > <= >=
• Logical: && || !, Nil-coalescing: ??
• Range: ..< (half-open), ... (closed)
• Optional chaining: ?. and try? for graceful error handling.

Tooling

• Xcode and Swift Playgrounds for IDE and prototyping.
• Swift Package Manager (`swift build`, `swift test`) manages dependencies.
• SwiftLint enforces style; SwiftFormat auto-formats.
• Instruments and Xcode Organizer profile memory, energy, and performance.

Best Practices

• Use `guard` to exit early and keep happy-path indentation shallow.
• Prefer structs with immutable properties; leverage copy-on-write.
• Annotate concurrency domains clearly with `@MainActor` and Task priorities.
• Adopt unit/UI tests with XCTest and snapshot frameworks.

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