autojanet/skills/understand/languages/swift.md

Swift Language Prompt Snippet

Key Concepts

• Optionals and Optional Chaining: Type? wraps values that may be nil; ?. chains safely
• Protocols and Protocol Extensions: Define contracts with default implementations via extensions
• Value Types vs Reference Types: Structs and enums are value types; classes are reference types
• Closures: Self-contained blocks of functionality that capture surrounding context
• Property Wrappers: @State, @Binding, @Published encapsulate property storage logic
• Result Builders: @ViewBuilder, @resultBuilder enable declarative DSL syntax
• Actors and Structured Concurrency: actor types for data isolation; async let, TaskGroup
• Generics: Type parameters with where clauses and associated type constraints
• Enums with Associated Values: Each case can carry distinct typed payloads
• Extensions: Add methods, computed properties, and protocol conformance to existing types

Import Patterns

• import Foundation — core library with data types, collections, networking
• import UIKit — iOS UI framework for traditional view controller architecture
• import SwiftUI — declarative UI framework with reactive state management
• @testable import ModuleName — import with internal access for unit testing

File Patterns

• Package.swift — Swift Package Manager manifest defining targets and dependencies
• *.xcodeproj / *.xcworkspace — Xcode project and workspace configuration
• AppDelegate.swift — UIKit application lifecycle entry point
• App.swift — SwiftUI application entry point using @main
• Tests/ — test target directory following SPM or Xcode conventions

Common Frameworks

• SwiftUI — Declarative UI framework with reactive data flow
• UIKit — Imperative UI framework using view controllers and Auto Layout
• Vapor — Server-side Swift web framework with async support
• Combine — Reactive framework for processing values over time
• Core Data — Object graph and persistence framework

Example Language Notes

Uses @Published property wrapper to automatically notify SwiftUI views of state changes. When the wrapped value mutates, the property wrapper triggers objectWillChange on the enclosing ObservableObject, causing dependent views to re-render.

Protocol extensions provide default implementations, allowing types to conform by simply declaring conformance — no method body needed if defaults suffice.