# Lookatitude Guild Mobile IOS Swift > mobile-ios-swift - Skill: `tomevault-io/lookatitude-guild-mobile-ios-swift` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/lookatitude-guild-mobile-ios-swift` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/lookatitude-guild-mobile-ios-swift/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/lookatitude-guild-mobile-ios-swift --- # mobile-ios-swift Implements `guild-plan.md §6.1` (mobile · ios-swift) under `§6.4` engineering principles: idiomatic Swift, compiler-enforced safety, and concurrency that the language actually tracks. ## What you do Write Swift that the compiler helps keep correct. Pick SwiftUI when the minimum deployment target allows and the screen is data-driven; fall back to UIKit when custom transitions, legacy integration, or fine control demand it. Use Swift Concurrency (`async/await`, actors) rather than GCD unless interop requires it. - Prefer `let`, value types, and protocol-oriented composition over inheritance. - Use optional binding (`if let`, `guard let`) and typed throws — `!` is a smell. - Mark UI work `@MainActor`; keep I/O off the main thread with `Task.detached` or `async` functions. - Manage references: `[weak self]` in closures that outlive the owner, break retain cycles explicitly. - Use structured concurrency (`TaskGroup`, `async let`) for parallel work; cancel cooperatively. - Accessibility first: `accessibilityLabel`, Dynamic Type, VoiceOver checked. ## Output shape Swift source files plus a short build note: 1. **Source** — one file per logical unit; follow Apple's API Design Guidelines. 2. **Previews** — `#Preview` for SwiftUI, snapshot tests for UIKit. 3. **Build notes** — SPM dependency additions, minimum iOS target, Xcode scheme impact. 4. **Tests** — XCTest file exercising the non-UI logic. 5. **Accessibility** — a short checklist pass (labels, traits, Dynamic Type). ## Anti-patterns - Force-unwraps (`!`) and forced casts (`as!`) in production paths. - Retain cycles in `self`-capturing closures (timers, Combine sinks, callbacks). - Main-thread blocking: `DispatchQueue.main.sync`, disk / network on UI calls. - `@ObservedObject` on a model the view owns — use `@StateObject`. - Massive view controllers / massive views — extract models and view models. - Swallowed errors with `try?` where a real error path exists. ## Handoff Return the Swift source paths and build notes to the invoking `mobile` specialist. If the feature needs Android parity, the mobile agent chains into `mobile-android-kotlin`; for cross-platform, `mobile-react-native`. Performance tuning lives in `mobile-performance-tuning`. This skill does not dispatch. --- > Source: [lookatitude/guild](https://github.com/lookatitude/guild) — distributed by [TomeVault](https://tomevault.io).