IOS Dependency Injection

iOS Dependency Injection

Priority: P0 (CRITICAL)

Implementation Workflow

1. Prefer initializer injection — Pass dependencies through init as primary approach.
2. Inject protocols — Always depend on protocols instead of concrete classes for testability.
3. Choose DI library — Use Factory for lightweight DI, Swinject for enterprise-grade container-based projects.
4. Apply correct scoping — Singleton for app-wide services (Auth, Network); Unique/Transient for ViewModels; Graph/Cached for feature flows.

See protocol-based DI and Factory registration examples

Anti-Patterns

• No Global Singletons: Inject services via initializer
• No Inline Service Resolution: Pass dependencies via constructor; avoid Resolver.resolve() in business logic
• No Concrete Class Dependencies: Depend on protocols for testability

References

• Manual & Library DI Setup

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

• Injected

Remediation anchors

• Remediation anchors: protocol injection, Factory library, initializer injection