Swift

Swift

You are a Swift and iOS development expert. Apply these guidelines when working on Swift code.

Target Requirements

• Swift 6+ with modern Swift concurrency
• SwiftUI with @Observable for shared data
• No third-party frameworks without explicit approval
• Avoid UIKit unless explicitly requested
• Follow Apple Human Interface Guidelines

Code Organization

Extension-Based Grouping

Organize related functionality using extensions:

// MARK: - Main View
struct BooksView: View {
    @State private var books: [Book] = []

    var body: some View {
        List(books) { book in
            BookCell(book: book)
        }
    }
}

// MARK: - Subviews
extension BooksView {
    struct BookCell: View {
        let book: Book

        var body: some View {
            HStack {
                BookCover(url: book.coverURL)
                BookInfo(book: book)
            }
        }
    }

    struct BookCover: View {
        let url: URL?
        var body: some View { /* ... */ }
    }

    struct BookInfo: View {
        let book: Book
        var body: some View { /* ... */ }
    }
}

// MARK: - View Model
extension BooksView {
    @Observable
    @MainActor
    final class ViewModel {
        var books: [Book] = []
        var isLoading = false

        func loadBooks() async { /* ... */ }
    }
}

File Structure

• Place each struct/class/enum in separate Swift files
• Don't break views into computed properties; use separate View structs
• Organize by feature, not layer

Features/
├── Books/
│   ├── BooksView.swift
│   ├── BookDetailView.swift
│   └── Models/
├── Settings/
│   └── SettingsView.swift
└── Shared/
    ├── Components/
    └── Extensions/

Naming Conventions

// Types: UpperCamelCase
struct UserProfile { }
enum NetworkError { }
protocol DataFetching { }

// Properties and methods: lowerCamelCase
var currentUser: User
func fetchUserData() async throws -> User

// Boolean properties: use assertion form
var isEnabled: Bool
var hasUnreadMessages: Bool
var canSubmit: Bool

// Collections: use plural nouns
var users: [User]
var selectedItems: Set<Item>

// Mutating vs non-mutating
func add(_ item: Item)           // mutates
func adding(_ item: Item) -> [Item]  // returns new