15.1 · MVC, MVVM, MVP, VIPER, RIBs, TCA and Clean, and unidirectional data flow

Every architecture answers the same few questions: where does state live, who is allowed to change it, and how do you test it. The names differ; the trade-offs mostly do not.

Mental model. Architecture is where you draw the lines. A good line makes one thing easy to test and one kind of change cheap; each extra line costs code and indirection.

Choosing a pattern

The family of patterns and their honest costs.

1. How do MVC, MVVM, MVP, VIPER, RIBs and Clean compare, and which would you choose? 15.1.1 · L2
   All of them separate what to show from how to show it, and differ in how many layers they add. MVC (Apple’s original) has a model, a view and a controller that…

One-way state

Unidirectional data flow and reducers.

1. What is unidirectional data flow, and how does a reducer make state changes predictable and testable? 15.1.2 · L3
   Unidirectional data flow means state changes travel in one loop: the view renders from a single state; user input and system events become actions (plain…

More in Architecture & API design

• 15.2 · Coordinators, routers and dependency injection
• 15.3 · Feature modules and boundaries, and strangling a legacy codebase
• 15.4 · throws, Result, typed throws and mapping errors at boundaries
• 15.5 · Designing a Swift API: naming, ownership, documentation and evolution
• 15.6 · SOLID without dogma, and building a platform for many apps
• 15.7 · Effects and cancellation, modelling state, composing reducers
• 15.8 · Closure-based clients, dependency lifetimes, generic repositories and building the graph lazily
• 15.9 · Binary breaks from innocent changes, and what an import exposes
• 15.10 · Types that prevent misuse, error types for libraries, one-shot values and when to trap