Transforming RealityKit entities using gestures

At a glance

Project structure

Source bundle/
├── EntityGestures/
│   ├── EntityGestureApp.swift
│   ├── ContentView.swift
│   └── Info.plist
├── Packages/
│   └── RealityKitContent/
│       ├── Sources/
│       │   └── RealityKitContent/
│       │       ├── Components/
│       │       │   └── GestureComponent.swift
│       │       ├── Extensions/
│       │       │   ├── EntityExtensions.swift
│       │       │   ├── GestureExtensions.swift
│       │       │   └── RealityViewExtensions.swift
│       │       └── RealityKitContent.swift
│       └── Package.swift
├── Configuration/
│   └── SampleCode.xcconfig
└── EntityGestures.xcodeproj/
    ├── .xcodesamplecode.plist
    └── project.pbxproj

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 4 source declaration(s).

Overall architecture

flowchart LR
    N1["EntityGestureApp"]
    N2["ContentView"]
    N3["RealityKit / RealityKitContent APIs"]
    N1 --> N2
    N2 --> N3

Reference code

EntityGestures/EntityGestureApp.swift:11 — architecture anchor

@main
struct EntityGestureApp: App {

    init() {
        RealityKitContent.GestureComponent.registerComponent()
    }

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .windowStyle(.volumetric)
        .defaultSize(width: 2, height: 1.75, depth: 1, in: .meters)
    }
}

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 RealityKit.

Ownership and state

classDiagram
    EntityGestureState o-- Entity : targetedEntity
    EntityGestureState *-- SIMD3 : dragStartPosition
    EntityGestureState o-- Entity : pivotEntity
    EntityGestureState o-- simd_quatf : initialOrientation

Ownership evidence

Packages/RealityKitContent/Sources/RealityKitContent/Components/GestureComponent.swift:14 — stored dependency or nearest verified ownership anchor

public class EntityGestureState {
    // ...
    var targetedEntity: Entity?
    // ...
}

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

EntityGestures/ContentView.swift:52 — representative execution boundary

                if let scene = try? await Entity(named: "Scene", in: realityKitContentBundle) {
                    content.add(scene)
                }

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

EntityGestures/EntityGestureApp.swift:12 — representative type boundary

@main
struct EntityGestureApp: App {
    // ...
        RealityKitContent.GestureComponent.registerComponent()
    // ...
}

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

Access control

Reference code

Packages/RealityKitContent/Sources/RealityKitContent/Components/GestureComponent.swift:58 — representative boundary

@MainActor
public struct GestureComponent: Component, Codable {
    // ...
    public var canDrag: Bool = true
    // ...
}

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: EntityGestureApp; Component: GestureComponent; View: ContentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: onChanged, handlePivotDrag, handleFixedDrag, onEnded, useGestureComponent, installGestures.
• Files: EntityGestures/EntityGestureApp.swift, Packages/RealityKitContent/Sources/RealityKitContent/Components/GestureComponent.swift, EntityGestures/ContentView.swift.

Architecture takeaways

• EntityGestureApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches RealityKit, SwiftUI, RealityKitContent, PackageDescription 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