viper-architecture-rambler

VIPER Architecture (Rambler Team)

Overview

VIPER enforces Single Responsibility Principle through five protocol-based components: View, Interactor, Presenter, Entity, Router. Created and documented by Rambler&Co iOS Team.

Core Principle: Entities never reach the Presentation layer. Simple data structures transfer between Interactor and Presenter, preventing business logic pollution in UI.

When to Use VIPER

digraph viper_decision {
    "Complex app?" [shape=diamond];
    "Multiple features?" [shape=diamond];
    "Long-term project?" [shape=diamond];
    "Team size > 2?" [shape=diamond];
    "High testability need?" [shape=diamond];
    "Use VIPER" [shape=box, style=filled, fillcolor=lightgreen];
    "Use MVC/MVVM" [shape=box, style=filled, fillcolor=lightcoral];

    "Complex app?" -> "Multiple features?" [label="yes"];
    "Complex app?" -> "Use MVC/MVVM" [label="no"];
    "Multiple features?" -> "Long-term project?" [label="yes"];
    "Multiple features?" -> "Use MVC/MVVM" [label="no"];
    "Long-term project?" -> "Team size > 2?" [label="yes"];
    "Long-term project?" -> "High testability need?" [label="no"];
    "Team size > 2?" -> "Use VIPER" [label="yes"];
    "Team size > 2?" -> "High testability need?" [label="no"];
    "High testability need?" -> "Use VIPER" [label="yes"];
    "High testability need?" -> "Use MVC/MVVM" [label="no"];
}

Use VIPER for:

• Multi-feature apps (authentication, payments, user profiles, etc.)
• Long-term projects (6+ months)
• Teams with 3+ developers
• Apps requiring extensive unit test coverage
• Multi-platform code sharing (iOS/iPadOS/macOS)

Avoid VIPER for:

• Single-screen utilities
• Rapid prototypes with unclear requirements
• Weekend projects or proof-of-concepts
• Small teams with tight deadlines

Component Responsibilities

Component	Responsibility	What It Must NOT Do
View	Display content, relay user input (passive)	Request data, format data, navigation, business logic
Interactor	Business logic, use cases (platform-independent)	UI updates, formatting, routing, direct Core Data access
Presenter	View logic, data formatting (bridges logic & display)	Business logic, network calls, data persistence
Entity	Plain model objects (PONSOs - no behavior)	Logic, formatting, self-persistence
Router	Navigation, module assembly	Business logic, data management, UI updates