Overview › Dependency Injection

Dependency Injection

Native init-based DI, no formal framework; brittle for testing at scale.

0 findings in this category · iOS

SCORE

Summary

iOS does not use a formal DI framework (no Swinject, Resolver, Factory). Dependencies are passed through initializers and feature ViewModels accept their collaborators as init parameters. This is fine for small modules but makes test setup verbose for ViewModels with many dependencies.

How DI is currently done

Layer	Mechanism	Notes
Feature ViewModels	Initializer injection of protocols defined in `Core`	Tests substitute Mockey-generated mocks or hand-written fakes
Network client	Singleton-style instance configured in `CoreImplementation`	Acceptable for a service with no per-screen state
Storage	Protocol-based; concrete instance from `Storage` SPM	Clean
Composition root	Spread across feature flow controllers	No central composition
SwiftUI environment	Limited use of `@Environment` for cross-cutting deps	Opportunity

Recommended pattern

For a codebase this size, a lightweight Factory registry (similar to the Hmlongco/Factory library) gives you:

Centralized declaration of dependencies in one file per package.
Auto-resolution into ViewModels via @Injected or initializer.
Easy test-time substitution via register.
Compile-time visibility into the dependency graph.

Alternative: stay with manual initializer DI but introduce one Composer per feature that owns the wiring.

Findings

PASS

Init-based DI is explicit and Swift-idiomatic

No magic; every dependency is visible at the call site.

MEDIUM

Verbose test setup in ViewModels with many deps

NewOnboardingViewModelTest equivalent — when a ViewModel has 30+ collaborators, every test sets up 30+ mocks.

Recommendation: Extract collaborators into use cases; ViewModel tests then mock 1-3 use cases.

MEDIUM

No central composition root

Object graph wiring is spread across the app — adding a new dependency requires touching multiple files.

Recommendation: Adopt a lightweight Factory pattern (e.g. Hmlongco's Factory library) or build a small Composer at the app boundary.

LOW

SwiftUI `@Environment` as pseudo-DI

For SwiftUI views, @Environment is a low-friction DI mechanism for cross-cutting deps.

Recommendation: Define EnvironmentValues entries for analytics, theming, feature flags.

No findings logged in this category yet for iOS.

Costco iOS · Code Review Report · Generated 2026-05-07 · 88 machine-curated findings