swift-architecture

name	swift-architecture
description	Swift architecture patterns and playbooks for MVVM, TCA, Clean Architecture, and more.
license	MIT

Swift Architecture Skill

Overview

Use this skill to pick the best Swift architecture playbook for SwiftUI/UIKit codebases and apply it to the user’s task.

For quick navigation across playbooks, use references/_index.md.

Workflow

Step 1: Analyze the Request Context

Before selecting an architecture, capture:

• task type (new feature, refactor, PR review, debugging)
• UI stack (SwiftUI, UIKit, or mixed)
• scope (single screen, multi-screen, app-wide)
• state and effect complexity
• team familiarity and dependency tolerance
• existing conventions to preserve

Then choose a delivery mode for the rest of the workflow:

• Quick Recommendation Mode — use when the scope is one feature or screen, constraints are clear enough to recommend one primary pattern, and the user mainly needs a recommendation, scaffold, or review checklist. Deliver: fit result (fit or mismatch), 1-2 reasons grounded in the request, the selected reference file, and concrete structure, state, dependency, async, and testing guidance scoped to the feature.
• Deep Refactor Mode — use when the request spans multiple modules or screens, the codebase already mixes architectures, or the user is migrating from one pattern to another. Deliver: current-state assessment, target architecture recommendation with fit or mismatch result, an incremental migration path with boundary changes called out, and risks, trade-offs, and verification points for the transition.

Step 2: Select the Architecture

If the user explicitly names an architecture, treat it as the initial candidate and run a fit check before committing:

• validate against UI stack fit (SwiftUI/UIKit/mixed), state complexity, effect orchestration needs, team familiarity, and existing codebase conventions
• if it fits, proceed with the requested architecture
• if it mismatches key constraints, explicitly explain the mismatch and recommend the closest-fit alternative from references/selection-guide.md
• if the user still insists on a mismatched architecture, proceed with a risk-mitigated plan and state the risks up front

When no architecture is named, load references/selection-guide.md and infer the best fit from stated constraints (state complexity, team familiarity, testing goals, effect orchestration needs, and framework preferences). Explain the recommendation briefly.

Architecture reference mapping:

• MVVM → references/mvvm.md
• MVI → references/mvi.md
• TCA → references/tca.md
• Clean Architecture → references/clean-architecture.md
• VIPER → references/viper.md
• Reactive → references/reactive.md
• MVP → references/mvp.md
• Coordinator → references/coordinator.md

Step 3: Analyze Existing Codebase (When Applicable)

When code already exists:

• detect current architecture and DI style
• note concurrency model (async/await, Combine, GCD, mixed)
• align recommendations to local conventions

Guardrails

• Do not force an architecture switch for a small feature when the current local pattern is still a reasonable fit.
• Preserve existing conventions unless the mismatch is severe enough to justify change.
• Do not introduce new framework dependencies such as TCA unless the user explicitly accepts that trade-off or the codebase already uses them.
• Prefer the smallest architecture change that solves the request cleanly.
• Keep guidance architecture-specific; do not blend playbooks unless the boundary between patterns is explicit.

Step 4: Produce Concrete Deliverables

Read the selected architecture reference and convert its guidance into deliverables tailored to the user's request:

• File and module structure: directory layout with file names specific to the feature
• State and dependency boundaries: concrete types, protocols, and injection points
• Async strategy: cancellation, actor isolation, and error paths
• Testing strategy: what to test, how to stub dependencies, and example test structure
• Migration path (for refactors): incremental steps to move from current to target architecture
• UI stack adaptation: where SwiftUI and UIKit guidance should differ for the chosen architecture

Step 5: Validate with Checklist

End with the architecture-specific PR review checklist from the reference file, adapted to the user's feature.

Output Requirements

• Keep recommendations scoped to the requested feature or review task.
• Prefer protocol-based dependency injection and explicit state modeling.
• Flag anti-patterns found in existing code and provide direct fixes.
• Include cancellation and error handling in all async flows.
• For explicit architecture requests, include a short fit result (fit or mismatch) with 1-2 reasons.
• For mismatch cases, include one closest-fit alternative and why it better matches the stated constraints.
• When writing code, include only the patterns relevant to the task — do not dump entire playbooks.
• Treat reference snippets as illustrative by default; add full compile scaffolding only if the user asks for runnable code.
• Ask only minimum blocking questions; otherwise proceed with explicit assumptions stated up front.
• When reviewing PRs, use the architecture-specific checklist and call out specific violations with line-level fixes.