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
Factorylibrary for lightweight, type-safe navigation-friendly DI. - Swinject: Use for enterprise-grade container-based DI in large modular projects.
- Injected: Use
@Injectedproperty 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