Responding to gestures on an entity

At a glance

Project structure

Source bundle/
└── GestureResponse/
    ├── ContentView.swift  # ActiveComponent, ContentView
    └── GestureResponseApp.swift  # GestureResponseApp

Structure observations

• The runtime boundary is WindowGroup; the tree is pruned to lifecycle, state, framework, rendering, and ECS files.
• The source is Swift; its compact size does not erase any explicit owner shown below.

Overall architecture

flowchart LR
    GestureResponseApp_1["GestureResponseApp"]
    WindowGroup_2["WindowGroup"]
    ContentView_3["ContentView"]
    RealityKit_entity_graph_4["RealityKit entity graph"]
    targeted_gestures___entity_state_5["targeted gestures + entity state"]
    GestureResponseApp_1 --> WindowGroup_2
    WindowGroup_2 --> ContentView_3
    ContentView_3 --> RealityKit_entity_graph_4
    RealityKit_entity_graph_4 --> targeted_gestures___entity_state_5

Reference code

GestureResponse/GestureResponseApp.swift:10 — executable or app-lifecycle anchor.

struct GestureResponseApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
     }
}

The diagram is a responsibility flow, not a claim that every adjacent node directly calls the next. It separates lifecycle, presentation, stable state, framework/session work, and the RealityKit entity graph.

Ownership and state

classDiagram
    ContentView --> ModelEntity : cube

Ownership evidence

GestureResponse/ContentView.swift:18 — representative stored state or nearest verified lifecycle anchor.

struct ContentView: View {
    var cube: ModelEntity
    // ...
}

Ownership is intentionally narrow: environment, bindings, observed objects, weak links, and delegate callbacks do not prove lifetime ownership. Initialized stored services and wrapper-managed state do; entities added inside a RealityKit content closure belong to that entity graph.

Class and protocol design

The reviewed source defines no local substitution protocol. Its App, View, delegate, renderer, ARKit, and RealityKit conformances are framework-facing contracts, so this document does not label the whole app protocol-oriented.

Access control

No reviewed Swift access example uses fileprivate, private(set), open; declarations without a modifier are internal.

Reference code

GestureResponse/ContentView.swift:14 — representative visibility boundary.

@Observable
public class ActiveComponent: Component {
    public var active: Bool = false
}

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: App: GestureResponseApp; Component: ActiveComponent; View: ContentView.
• ECS names pair data and behavior: components ActiveComponent; systems none.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: the compact sample has no separate command layer.
• Files and folders use primary-type or responsibility names such as Views, Models, Rendering, Components, Systems, Packages, or feature names where those boundaries exist.

Architecture takeaways

• Treat GestureResponseApp as the owner of executable or scene lifecycle, not automatically as the owner of every entity created later.
• Keep view/controller input near presentation, but move sessions, reconstruction, capture, rendering, shared game state, or documents into stable owners when their lifetime exceeds one callback or render pass.
• The compact source does not justify repository, coordinator, or protocol layers beyond boundaries the sample actually declares.

Source map

• Official Apple documentation