| name | ios-developer-competency-matrix |
| description | Professional iOS development competency coverage across Swift language mastery, SwiftUI + UIKit UI development, architecture/patterns (MVVM, Coordinator, Clean), networking/data/persistence, platform capabilities (lifecycle, background, device features), accessibility, testing/debugging/performance, and CI/CD + App Store distribution. Use when implementing or reviewing iOS code for best-practice patterns, concurrency/thread-safety, memory/ARC issues, architecture decisions, data layers, testing strategy, or release readiness. |
iOS Developer Competency Matrix
Use this skill as a review + implementation checklist when building features in this repo.
1) Quick triage questions (pick the right lane)
Answer these before coding:
- Is this mostly UI (SwiftUI/UIKit), domain logic, data/network, or platform integration?
- Do we need async work? If yes: can we use structured concurrency end-to-end?
- What are the states (loading/empty/error/success) and how are they represented?
- What must be testable (unit/UI/snapshot) and what is the acceptance criteria?
2) Swift language & concurrency rules
- Prefer Swift concurrency (
async/await) over nested completion handlers.
- UI mutations on the main actor (
@MainActor / await MainActor.run).
- Use actors or isolated types for shared mutable state.
- Watch for ARC traps: closures capturing
self → use [weak self] when needed.
3) UI (SwiftUI + UIKit)
- SwiftUI: choose the right state tool (
@State, @Binding, @StateObject, @ObservedObject, @Environment).
- UIKit: respect lifecycle, safe areas, and Auto Layout anchors.
- Interop:
- SwiftUI in UIKit:
UIHostingController
- UIKit in SwiftUI:
UIViewRepresentable / UIViewControllerRepresentable
4) Architecture & patterns
Default opinionated picks (override only with reason):
- SwiftUI screens: MVVM (View + ViewModel + injected services)
- Navigation complexity: add a Coordinator (or a routing layer)
- Scale/enterprise modules: consider Clean boundaries (domain/use-cases, repositories)
- Dependency injection: start with initializer injection; add a container only when it pays off.
5) Networking & data
- Prefer
URLSession + Codable with explicit domain errors.
- Model API errors → map to user-facing messages at the edge.
- Persistence: SwiftData/Core Data for relational graphs; Keychain for secrets; UserDefaults for prefs.
6) Platform integration
- Understand scene lifecycle vs app delegate responsibilities.
- For background work, pick the correct API (and keep expectations realistic).
- Device features (camera/location/push/biometrics): treat permission flows + failure paths as first-class.
7) Quality: tests, debugging, performance
- Unit tests for logic; UI tests for key flows; snapshot tests for UI regressions (if used here).
- Use Instruments for leaks/time/energy when performance matters.
8) Release readiness
- HIG alignment + accessibility basics.
- Review Guideline landmines: privacy disclosures, permissions strings, incomplete flows.
- CI/CD: prefer SPM; automate build/test; keep signing/provisioning sane.
References
- Deep checklists + snippets:
references/checklists.md
