Building a document-based app using SwiftData

At a glance

Project structure

Source bundle/
├── End/
│   └── FlashCard/
│       ├── SwiftDataFlashCardSample.swift
│       └── Views/
│           ├── CardEditorView.swift
│           ├── CardContainerView.swift
│           ├── CardReaderView.swift
│           ├── ContentView.swift
│           └── FlashCardView.swift
└── Start/
    └── FlashCard/
        ├── SwiftDataFlashCardSample.swift
        └── Views/
            ├── CardEditorView.swift
            ├── CardContainerView.swift
            ├── CardReaderView.swift
            ├── ContentView.swift
            └── FlashCardView.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Swift.
• The verified tree contains 10 project/configuration file(s) and 34 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["End"]
    V2["Start"]
    Boundary["SwiftUI APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

End/FlashCard/SwiftDataFlashCardSample.swift:11 — architecture anchor

@main
struct SwiftDataFlashCardSample: App {
    var body: some Scene {
        #if os(iOS) || os(macOS)
        DocumentGroup(editing: .flashCards, migrationPlan: FlashCardsMigrationPlan.self) {
            ContentView()
        }
        #else
        WindowGroup {
            ContentView()
                .modelContainer(previewContainer)
        }
        #endif
    }
}

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    CardEditorView o-- Card : card
    CardEditorView o-- FocusedField : focusedField
    CardContainerView o-- Content : content
    CardReaderView o-- Color : color

Ownership evidence

End/FlashCard/Views/CardEditorView.swift:11 — stored dependency or nearest verified ownership anchor

struct CardEditorView: View {
    @Bindable var card: Card
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

End/FlashCard/Support/PreviewSampleData.swift:10 — representative execution boundary

@MainActor

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

End/FlashCard/Views/CardEditorView.swift:10 — representative type boundary

struct CardEditorView: View {
    @Bindable var card: Card
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

End/FlashCard/Views/CardCarousel.swift:13 — representative boundary

struct CardCarousel: View {
    @State private var selectedCardID: PersistentIdentifier?
    // ...
}

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Naming conventions

• Types: View: CardContainerView, CardEditorView, CardReaderView, ContentView, FlashCardView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: makeBody.
• Files: End/FlashCard/SwiftDataFlashCardSample.swift, Start/FlashCard/SwiftDataFlashCardSample.swift, End/FlashCard/Views/CardEditorView.swift, Start/FlashCard/Views/CardEditorView.swift, End/FlashCard/Views/CardContainerView.swift, End/FlashCard/Views/CardReaderView.swift.

Architecture takeaways

• SwiftDataFlashCardSample is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, SwiftData, UniformTypeIdentifiers through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation