git-hardening/.crosslink/rules/swift.md

Swift Best Practices

Code Style

• Follow Swift API Design Guidelines
• Use camelCase for variables/functions, PascalCase for types
• Prefer let over var when possible
• Use optionals properly; avoid force unwrapping

// GOOD: Safe optional handling
func findUser(id: String) -> User? {
    guard let user = repository.find(id) else {
        return nil
    }
    return user
}

// Using optional binding
if let user = findUser(id: "123") {
    print(user.name)
}

// BAD: Force unwrapping
let user = findUser(id: "123")!  // Crash if nil

Error Handling

• Use throws for recoverable errors
• Use Result<T, Error> for async operations
• Handle all error cases explicitly

// GOOD: Proper error handling
func loadConfig() throws -> Config {
    let data = try Data(contentsOf: configURL)
    return try JSONDecoder().decode(Config.self, from: data)
}

do {
    let config = try loadConfig()
} catch {
    print("Failed to load config: \(error)")
}

Security

• Use Keychain for sensitive data
• Validate all user input
• Use App Transport Security (HTTPS)
• Never hardcode secrets