SwiftData

How I saved favorites on device while keeping Domain as plain structs.

Favorites persist with SwiftData. Places from Geoapify do not; they are fetched on demand and cached briefly on disk inside POIRepository.

Why SwiftData here?

Favorites need:

• Storage across app launches
• Simple queries (is this id saved? list all)
• No backend to sync with (study app scope)

I picked SwiftData over Core Data for less boilerplate at this size. Apple-native, @Model, ModelContext.

What I did

FavoritePOI (@Model) in Data. Domain POI stays a struct. FavoritesRepository maps both ways.

Why (then)

I wanted to practice “persistence model ≠ domain model” the same way DTOs differ from entities for Geoapify.

What I’d reconsider

If favorites were the only representation of a place and never came from an API, I might use @Model as the single source of truth and skip the mapper. Here both tabs show POI, so the struct stayed central.

Domain vs persistence model

Domain: POI (struct, value type, no framework).

Data: FavoritePOI (@Model class).

@Model
final class FavoritePOI {
  var id: String
  var name: String
  // ...
}

FavoritesRepository:

• add(_ poi: POI) → insert FavoritePOI(from: poi)
• fetchAll() → map models back to [POI]

ViewModels call FavoritesUseCase, which calls FavoritesRepositoryProtocol. SwiftData never appears in Presentation.

ModelContext wiring

PersistenceDependencies creates a ModelContainer for FavoritePOI.self and passes ModelContext into FavoritesRepository and FavoritesUseCase. Once, in DI, not in Views.

Favorites tab flow

1. FavoritesViewModel → FavoritesUseCase.fetchAll()
2. UseCase → repository
3. Repository fetches FavoritePOI rows, returns [POI]
4. ViewModel updates UI state
5. Swipe to delete → same chain

Detail uses the same UseCase for isFavorite and the heart button.

Could POI be @Model directly?

Yes. Simpler file count, one type for list and favorites. Downside: Domain would depend on SwiftData, and API-sourced fields (live Geoapify data) mix with persisted rows. I kept them separate to learn the mapper; I might merge on a production app if the domain model matched persistence 1:1.

Could I use UserDefaults or a JSON file?

Yes for a handful of favorites. SwiftData felt worth learning for queries and relationships if the app grew (folders, notes, sync later).

Read next

• Repositories & Services
• Domain