Software Development Skills

Audit an existing iOS codebase, detect the current architecture (or closest match), score it across nine parameters, and produce either a refactor plan to improve it in place OR a migration recommendation. Use when the user asks for a codebase audit, refactor planning, "what architecture do we have", or wants to know if it's worth migrating.

Layered Clean Architecture for iOS — Domain (Entities, Use Cases, Repository protocols), Data (DTOs, repository impls), Presentation (any UI pattern, MVVM by default). Dependency rule outer→inner. Use for medium/large apps with non-trivial domain logic.

Clean Swift (VIP) by Raymond Law. Strict V → I → P → V cycle, per-boundary Request/Response/ViewModel structs, Worker for repo access. Use for TDD-committed UIKit teams; avoid in SwiftUI.

Modular / TMA (The Modular Architecture) — each feature is a Tuist or SPM module with Interface, Sources, Tests, Example targets. Orthogonal to in-module pattern (MVVM, TCA, etc.). Use for medium-to-large teams (≥5 devs or ≥30 screens).

Apple Cocoa MVC for iOS (UIKit). Use when implementing or refactoring against the default Apple sample-code pattern. Reject for production apps that will scale past 20 screens.

Model-View-Presenter for UIKit. Passive View + Presenter holding presentation logic. Use when migrating MVC towards testability without taking on Combine/Rx.

MVVM + Coordinator. UIKit variant uses Coordinator classes owning UINavigationController. SwiftUI variant uses a typed Router with NavigationStack(path:). Use for UIKit medium/large apps with deep-linking or SwiftUI apps where NavigationStack alone is too thin.

MVVM for SwiftUI using the iOS 17 Observation framework (@Observable). Default for medium SwiftUI apps. Use when implementing or refactoring SwiftUI screens with non-trivial presentation logic.

MVVM for UIKit using Combine. ViewModel exposes @Published outputs + command methods; ViewController binds via Combine sinks. Use for medium UIKit codebases comfortable with Combine.

Redux / ReSwift for iOS. Single global store, pure reducers, actions, middleware for side effects. Use when sharing business logic across platforms or when a team has Redux background. Consider TCA first for greenfield SwiftUI.

Uber RIBs (Router-Interactor-Builder). Hierarchical RIB tree, RxSwift-driven, Builder/Component DI. Use only at Uber-scale teams (≥30 iOS engineers) with deeply nested state. Reject otherwise.

The Composable Architecture (TCA) by Point-Free, SwiftUI-first. @Reducer + @ObservableState, Effect-driven, exhaustive testing via TestStore. Use for correctness-critical greenfield SwiftUI apps with capacity to absorb the learning curve.

VIPER for UIKit. Five-component module per screen — View, Interactor, Presenter, Entity, Router — plus Builder. Use for large UIKit codebases with multi-team ownership or regulated domains. Reject for SwiftUI-first and small teams.

Migrate an iOS codebase from one architecture pattern to another. Covers all 12×12 source→target pairs across MVC, MVP, MVVM-UIKit, MVVM-SwiftUI, MVVM-C, VIPER, Clean Swift, Clean Architecture, TCA, Redux/ReSwift, RIBs, and Modular/TMA. Produces a phased plan with shared primitives, per-pair playbook, and rollback triggers. Use when the user wants to migrate, port, or replace the architecture of an existing iOS project.