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At a glance

Project structure

Source bundle/
├── Shared/
│   ├── EarthquakesApp.swift
│   ├── Models/
│   │   ├── Quake.swift
│   │   ├── QuakesProvider.swift
│   │   └── QuakeError.swift
│   ├── ContentView.swift
│   ├── Toolbar Content/
│   │   ├── DeleteButton.swift
│   │   ├── RefreshButton.swift
│   │   └── ToolbarStatus.swift
│   └── Views/
│       └── QuakeDetail.swift
├── Earthquakes-macOS/
│   └── ContentView.swift
└── Earthquakes-iOS/
    └── Toolbar Content/
        ├── SelectButton.swift
        └── EditButton.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 4 project/configuration file(s) and 20 source declaration(s).

Overall architecture

flowchart LR
    N1["EarthquakesApp"]
    N2["ContentView"]
    N3["QuakesProvider"]
    N4["SwiftUI APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

Shared/EarthquakesApp.swift:10 — architecture anchor

@main
struct EarthquakesApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, QuakesProvider.shared.container.viewContext)
        }
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into SwiftUI.

Ownership and state

classDiagram
    Quake *-- Float : magnitude
    Quake *-- String : place
    Quake *-- Date : time
    Quake *-- String : code

Ownership evidence

Shared/Models/Quake.swift:18 — stored dependency or nearest verified ownership anchor

    @NSManaged var magnitude: Float
    @NSManaged var place: String
    @NSManaged var time: Date

    // A unique identifier used to avoid duplicates in the persistent store.
    // Constrain the Quake entity on this attribute in the data model editor.
    @NSManaged var code: String

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.

Class and protocol design

Shared/EarthquakesApp.swift:11 — representative type boundary

struct EarthquakesApp: App {
    // ...
}

RootCodingKeys, FeatureCodingKeys, and the nested CodingKeys enum describe the incoming JSON decoding schema. They are intentionally omitted from architectural roles and ownership because they don’t own feature state or behavior.

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

Access control

Reference code

Earthquakes-macOS/ContentView.swift:15 — representative boundary

    private var lastUpdated = Date.distantFuture.timeIntervalSince1970

    @FetchRequest(sortDescriptors: [
        NSSortDescriptor(keyPath: \Quake.time, ascending: false)
    ])
    private var quakes: FetchedResults<Quake>

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: App: EarthquakesApp; Provider: QuakesProvider; View: ContentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: update, makePreviews, newTaskContext, fetchQuakes, importQuakes, newBatchInsertRequest, deleteQuakes, fetchPersistentHistory.
• Files: Shared/EarthquakesApp.swift, Shared/Models/Quake.swift, Shared/Models/QuakesProvider.swift, Earthquakes-macOS/ContentView.swift, Shared/ContentView.swift, Earthquakes-iOS/Toolbar Content/SelectButton.swift.

Architecture takeaways

• EarthquakesApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, CoreData 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