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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

class Quake: NSManagedObject {
    // ...
    @NSManaged var magnitude: Float
    // ...
}

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

Earthquakes-macOS/ContentView.swift:49 — representative execution boundary

    private func deleteQuakes(for codes: Set<String>) async {
        // ...
            let quakesToDelete = quakes.filter { codes.contains($0.code) }
        // ...
    }

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

Shared/EarthquakesApp.swift:11 — representative type boundary

@main
struct EarthquakesApp: App {
    // ...
            ContentView()
    // ...
}

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

struct ContentView: View {
    // ...
    private var lastUpdated = Date.distantFuture.timeIntervalSince1970
    // ...
}

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