IOS Dependency Injection

Standards for Protocol-based DI, Property Wrappers, and Factory/Needle. Use when configuring dependency injection or factory patterns in iOS. (triggers: **/*.swift, @Injected, Resolver, Container, Swinject, register, resolve)

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iOS Dependency Injection Standards

Priority: P0

Implementation Guidelines

Protocol-Based DI (Manual)

  • Initializer Injection: Preferred method. Pass dependencies through init.
  • Abstractions: Inject protocols instead of concrete classes to facilitate testing (Mocks/Stubs).

Modern Property Wrappers (Factory/Resolver)

  • Factory: Use the Factory library for lightweight, type-safe navigation-friendly DI.
  • Swinject: Use for enterprise-grade container-based DI in large modular projects.
  • Injected: Use @Injected property wrappers for cleaner syntax in ViewModels.

Scoping

  • Singleton: Use for app-wide services (Auth, Network, Database).
  • Unique/Transient: Default for ViewModels and temporary workers.
  • Graph/Cached: Use for shared data within a specific feature flow (Coordinator scope).

Anti-Patterns

  • No global singleton access everywhere: Inject service via initializer.
  • No Resolver.resolve() inside logic: Pass dependency via constructor.
  • No direct class instantiation: Depend on protocols for testability.

References

  • Manual & Library DI Setup

ComeOnOliver/skillshub/tree/main/skills/HoangNguyen0403/agent-skills-standard/ios-dependency-injection commit 9ab7d15a09

Frequently asked questions

npx skillmds@latest add comeonoliver/ios-dependency-injection