Clean Architecture

• Core: Essential, independent, and stable elements
• Outermost layer: Web/framework/DB, etc., elements that are easily changed during portability or technological transitions
• Outer layers depend on inner layers (not related to the flow of control)

https://www.slideshare.net/AtsushiNakamura4/clean-architecture-release

• Generalization rules of architecture
• Essence
  • Dependencies should only be directed towards higher-level policies (one-way)
  • Separate and control the flow of control from the direction of dependencies
• Example of potential problem: Dependency on a database
  • If written normally, the code that calls the DB becomes dependent on the DB
  • If the arrow of dependency points towards the DB, the arrow of dependency in the opposite direction of the domain (center of the diagram) will be created
  • Solution
    • Consider the flow of control and the direction of dependencies separately
    • The flow of control naturally goes from the code to the DB because it accesses the DB
    • Reverse the direction of dependencies
      • Modify the design of the DB to align with the code
      • Resolve it by following the style of the code

Introduction to iOS App Design Patterns §

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iOSDC2020 §

• Enterprise Business Rule
  • Center of the concentric circles
  • Logic that does not change depending on the app
  • For example, in a Reversi app, the rules of Reversi itself
    • There may be Reversi apps for playing against AI or against other players, but the Enterprise Business Rule is the part that does not change regardless of these variations.