Making a card game with drag, drop, and reordering in SwiftUI

At a glance

Project structure

Source bundle/
├── SwiftUI-Reorderable/
│   ├── SwiftUI-Reorderable/
│   │   ├── SwiftUIReorderableApp.swift
│   │   ├── Views/
│   │   │   ├── CardView.swift
│   │   │   ├── PileView.swift
│   │   │   ├── DestinationView.swift
│   │   │   ├── GameView.swift
│   │   │   └── RemainderView.swift
│   │   ├── ContentView.swift
│   │   └── Game/
│   │       ├── CardValue.swift
│   │       ├── Card.swift
│   │       └── Game.swift
│   └── SwiftUI-Reorderable.xcodeproj/
│       └── .xcodesamplecode.plist
└── Configuration/
    └── SampleCode.xcconfig

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 5 project/configuration file(s) and 21 source declaration(s).

Overall architecture

flowchart LR
    N1["SwiftUIReorderableApp"]
    N2["ContentView"]
    N3["SwiftUI APIs"]
    N1 --> N2
    N2 --> N3

Reference code

SwiftUI-Reorderable/SwiftUI-Reorderable/SwiftUIReorderableApp.swift:12 — architecture anchor

@main
struct SwiftUIReorderableApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(for: [Game.self, Card.self])
    }
}

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
    CardView o-- Card : card
    CardFaceView o-- CardValue : card
    PileView o-- Game : game
    PileView *-- Int : index

Ownership evidence

SwiftUI-Reorderable/SwiftUI-Reorderable/Views/CardView.swift:13 — stored dependency or nearest verified ownership anchor

struct CardView: View {
    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

SwiftUI-Reorderable/SwiftUI-Reorderable/Game/Card.swift:49 — representative execution boundary

    nonisolated enum Group: Hashable, Sendable {
        case pile(Int)
        // ...
    }

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

SwiftUI-Reorderable/SwiftUI-Reorderable/SwiftUIReorderableApp.swift:13 — representative type boundary

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

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

Access control

Reference code

SwiftUI-Reorderable/SwiftUI-Reorderable/ContentView.swift:12 — representative boundary

struct ContentView: View {
    @Environment(\.modelContext) private var modelContext
    // ...
}

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: SwiftUIReorderableApp; View: CardBackView, CardFaceView, CardPlaceholderView, CardView, ContentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: defaultValue, sizeThatFits, placeSubviews, makeCache, addGame, deleteSelectedGame, apply, incrementCardIndex.
• Files: SwiftUI-Reorderable/SwiftUI-Reorderable/SwiftUIReorderableApp.swift, SwiftUI-Reorderable/SwiftUI-Reorderable/Views/CardView.swift, SwiftUI-Reorderable/SwiftUI-Reorderable/Views/PileView.swift, SwiftUI-Reorderable/SwiftUI-Reorderable/ContentView.swift, SwiftUI-Reorderable/SwiftUI-Reorderable/Game/CardValue.swift, SwiftUI-Reorderable/SwiftUI-Reorderable/Views/DestinationView.swift.

Architecture takeaways

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