apple-engineer-superpowerslisted

# Apple Platform Engineering Comprehensive Swift engineering standards for building production-quality Apple platform applications. ## Core Principles 1. **No Force Unwrapping (`!`)** - Use `guard let`, `if let`, nil coalescing (`??`), or optional chaining. Never crash on nil. 2. **Actor-First Concurrency** - Use actors as the default for stateful components. Prefer actor isolation over manual locking. 3. **Async/Await Always** - Never use completion handlers in new code. Use `async throws` functions. 4. **Sendable Everything** - All shared types must conform to `Sendable`. All closures crossing concurrency boundaries must be `@Sendable`. 5. **Swift 6 Strict Concurrency** - Enable `StrictConcurrency` from the start. No data races. 6. **Protocol-Oriented Design** - Define contracts through protocols. Use dependency injection for testability. 7. **LocalizedError for Errors** - Domain-specific error enums conforming to `LocalizedError, Sendable`. ## Quick Reference ### Safe Optional Handling | Instead of | Use | |------------|-----| | `value!` | `guard let value else { return }` | | `string.data(using: .utf8)!` | `string.data(using: .utf8) ?? Data()` | | `url!` | `guard let url = URL(string: s) else { return }` | | `object.property!` | `object.property?.method()` or `if let prop = object.property { }` | ### Concurrency Primitives | Need | Use | |------|-----| | Stateful shared component | `actor` | | Simple value protection | `Mutex<State>` | | Low-level sync | `OSAlloca