viper-uikit

Approach: Production-First Iterative Refactoring — This skill is built for production enterprise codebases where stability and reviewability matter more than speed. Architecture changes are delivered through iterative refactoring — small, focused PRs (<=200 lines, single concern) tracked in a refactoring/ directory. AI tools consistently generate VIPER code with retain cycles, UIKit in Presenters, business logic in Presenters instead of Interactors, and strong references where weak ones are required. Every rule here exists to prevent those mistakes.

UIKit VIPER Architecture (iOS 13+)

Enterprise-grade UIKit VIPER architecture skill. Opinionated: prescribes passive Views (UIViewController IS the View), single-use-case Interactors, UIKit-free Presenters, protocol-isolated module boundaries, enum-based Builders with constructor injection, and optional Coordinator integration for multi-flow apps. VIPER's value is testability at scale — each layer is independently testable behind protocols. The tradeoff is boilerplate (5-15 files per module), which means code generation and consistent conventions are essential.

Architecture Layers

View (UIViewController) → Passive. Renders what Presenter says. Forwards user actions. Zero decisions.
Presenter              → Traffic cop. Translates Interactor data → ViewModels. Decides WHEN to navigate.
                         Imports Foundation ONLY — never UIKit.
Interactor             → Single use case. Business logic, data orchestration. Independent of UI.
                         Talks to Services/DataManagers via injected protocols.
Entity                 → Plain data structs (PONSOs). No behavior beyond computed properties.
Router/Wireframe       → HOW to navigate. Holds weak ref to ViewController. Performs push/present/dismiss.
Builder/Module         → Factory that assembles all components and wires references. Transient — creates and releases.

Ownership Chain (memorize this — most VIPER bugs are reference direction errors)