Monitoring fit and field of view fidelity
At a glance
| Item | Summary |
|---|---|
| Purpose | Respond to changes in fit and field of view fidelity on Apple Vision Pro by using the Visual Fidelity API. |
| App architecture | VisualFidelityApp composes WindowGroup + ImmersiveSpace around ContentView; AppModel coordinates ARKit provider updates and maps anchors into RealityKit content. |
| Main patterns | SwiftUI scene composition, SwiftUI–RealityKit bridge, Explicit immersive-space lifecycle, Observable state owner, Provider session boundary, Async update consumer |
| Project style | Code-rich sample with 8 scanned Swift file(s) and 690 Swift line(s); resources and generated assets are excluded from those counts. |
Project structure
Source bundle/
└── ARKit-VisualFidelity/
├── VisualFidelityApp.swift # VisualFidelityApp
├── Model/
│ └── AppModel.swift # AppModel, ImmersiveSpaceState, MonitoringState
└── Views/
├── ConfigurationView.swift # ConfigurationView
├── ContentView.swift # ContentView
├── ImmersiveView.swift # ImmersiveView
├── StatusView.swift # StatusView
├── ToggleMonitoringButton.swift # ToggleMonitoringButton
└── ToggleVisualizationButton.swift # ToggleVisualizationButton
Structure observations
- The runtime boundary is WindowGroup + ImmersiveSpace; the pruned tree lists only files that explain lifecycle, state, or framework integration.
- App code is split into role-named views, models, managers, providers, components, or systems.
Overall architecture
flowchart LR
VisualFidelityApp_1["VisualFidelityApp"]
WindowGroup___ImmersiveSpace_2["WindowGroup + ImmersiveSpace"]
ContentView_3["ContentView"]
AppModel_4["AppModel"]
RealityView_entity_graph_5["RealityView entity graph"]
ARKit_providers___RealityKit_6["ARKit providers + RealityKit"]
VisualFidelityApp_1 --> WindowGroup___ImmersiveSpace_2
WindowGroup___ImmersiveSpace_2 --> ContentView_3
ContentView_3 --> AppModel_4
AppModel_4 --> RealityView_entity_graph_5
RealityView_entity_graph_5 --> ARKit_providers___RealityKit_6
Reference code
ARKit-VisualFidelity/VisualFidelityApp.swift:11 — the app or executable entry declares the outer scene lifecycle.
struct VisualFidelityApp: App {
// ...
}The diagram is a responsibility flow, not a claim that every adjacent node directly calls the next. It keeps scene ownership, shared state, RealityKit content, and framework-provider work at separate levels.
Ownership and state
classDiagram
VisualFidelityApp *-- AppModel : appModel
ContentView o-- AppModel : appModel
AppModel --> MonitoringState : monitoringState
AppModel --> ImmersiveSpaceState : immersiveSpaceState
Ownership evidence
ARKit-VisualFidelity/VisualFidelityApp.swift:13 — representative stored state or the nearest verified lifecycle anchor.
@main
struct VisualFidelityApp: App {
// ...
@State private var appModel = AppModel()
// ...
}| Owner | Object or state | Relationship | Mutation authority |
|---|---|---|---|
VisualFidelityApp |
AppModel as appModel |
creates and retains | Only the declaring scope writes |
ContentView |
AppModel as appModel |
receives a shared/non-owning reference | The upstream owner controls lifetime; this scope may invoke its mutable API |
AppModel |
MonitoringState as monitoringState |
stores and coordinates | Only the declaring scope writes |
AppModel |
ImmersiveSpaceState as immersiveSpaceState |
stores and coordinates | The owning type coordinates writes |
Ownership here is deliberately narrow: @Environment and weak references are shared links, initialized @State or stored services are lifecycle ownership, and a RealityView content closure owns additions to its entity graph without making the SwiftUI view a reference-type owner.
Class and protocol design
| Type | Responsibility | Depends on or conforms to |
|---|---|---|
VisualFidelityApp (ARKit-VisualFidelity/VisualFidelityApp.swift:11) |
Declares app scenes and top-level dependency lifetime. | App |
ContentView (ARKit-VisualFidelity/Views/ContentView.swift:11) |
Presents UI and forwards gestures or lifecycle events. | View |
AppModel (ARKit-VisualFidelity/Model/AppModel.swift:13) |
Owns observable feature state and domain transitions. | Concrete framework collaborators |
ConfigurationView (ARKit-VisualFidelity/Views/ConfigurationView.swift:10) |
Presents UI and forwards gestures or lifecycle events. | View |
ImmersiveView (ARKit-VisualFidelity/Views/ImmersiveView.swift:12) |
Presents UI and forwards gestures or lifecycle events. | View |
StatusView (ARKit-VisualFidelity/Views/StatusView.swift:11) |
Presents UI and forwards gestures or lifecycle events. | View |
The source defines no local substitution protocol in the reviewed boundary. Its protocol use is framework-facing (App, View, RealityKit/ARKit protocols, or platform adapters), so this document does not label the whole app protocol-oriented.
Access control
| Symbol | Access | Verified effect | Likely rationale |
|---|---|---|---|
private(set) var monitoringState: MonitoringState = .stopped (ARKit-VisualFidelity/Model/AppModel.swift:45) |
private(set) |
The getter keeps its wider visibility, while mutation stays inside the declaring type and its permitted same-file extensions. | Inference: Protect a state invariant while allowing observation. |
private let logger = Logger(subsystem: "com.example.apple-samplecode.AR... (ARKit-VisualFidelity/Model/AppModel.swift:19) |
private |
Use is restricted to the declaration and same-file extensions permitted by Swift. | Inference: Hide implementation details and lifecycle-sensitive state. |
No reviewed declaration uses fileprivate, public, open; unmodified Swift declarations are internal.
Reference code
ARKit-VisualFidelity/Model/AppModel.swift:45 — representative visibility boundary.
@Observable
final class AppModel {
// ...
private(set) var monitoringState: MonitoringState = .stopped
// ...
}Logic ownership and placement
| Logic | Owning type or file | Placement rationale |
|---|---|---|
| Scene declaration and dependency lifetime | VisualFidelityApp |
The App/entry boundary determines window, volume, and immersive-space lifetime. |
| Presentation, attachments, and gestures | ContentView |
SwiftUI view code forwards user intent and RealityView lifecycle events. |
| Shared feature state and commands | AppModel |
A role-named owner prevents sibling views from duplicating transitions. |
| Tracking authorization and update streams | ARKit-VisualFidelity/Model/AppModel.swift:105 |
Provider lifetime and async updates remain outside render-only view code. |
Design patterns
| Pattern | Source evidence | Purpose or tradeoff |
|---|---|---|
| SwiftUI scene composition | ARKit-VisualFidelity/VisualFidelityApp.swift:11 |
Keeps windows, volumes, and immersive-space lifecycle visible at the app boundary. |
| SwiftUI–RealityKit bridge | ARKit-VisualFidelity/Views/ImmersiveView.swift:26 |
Builds and updates a RealityKit entity graph from SwiftUI lifecycle closures. |
| Explicit immersive-space lifecycle | ARKit-VisualFidelity/VisualFidelityApp.swift:24 |
Makes immersive presentation a scene transition rather than hidden global state. |
| Observable state owner | ARKit-VisualFidelity/Model/AppModel.swift:13 |
Shares feature state across multiple views without moving framework resources into view values. |
| Provider session boundary | ARKit-VisualFidelity/Model/AppModel.swift:105 |
Owns provider lifetime separately from the SwiftUI view tree. |
| Async update consumer | ARKit-VisualFidelity/Model/AppModel.swift:133 |
Consumes provider or event streams in cancellable structured tasks. |
Naming conventions
- Role suffixes are evidence, not decoration: App:
VisualFidelityApp; Model:AppModel; View:ConfigurationView,ContentView,ImmersiveView,StatusView. - Protocols: no app-defined protocol in the reviewed source.
- Commands use verb-led methods:
startMonitoring,stopMonitoring,monitor,apply,setAnchor,sync. - Files generally match their primary type;
Views,Models,Managers,Providers,Components,Systems, andPackagesfolders describe architectural roles where present.
Architecture takeaways
- Treat
VisualFidelityAppas the owner of scene declarations, not as the owner of every RealityKit entity created later. - Keep view-local interaction in SwiftUI, but move provider sessions, playback resources, shared game state, or transport state into a stable owner when their lifetime exceeds one render pass.
- Run ARKit providers for the scene lifetime and consume their asynchronous updates in cancellable tasks; map anchors to entities at the boundary.
- Model immersive-space open, transition, and close states explicitly so windows and immersive content cannot drift apart.
Source map
| Source file | Relevant symbols |
|---|---|
ARKit-VisualFidelity/VisualFidelityApp.swift:11 |
VisualFidelityApp |
ARKit-VisualFidelity/Model/AppModel.swift:13 |
AppModel, ImmersiveSpaceState, MonitoringState, FieldOfViewSelection |
ARKit-VisualFidelity/Views/ConfigurationView.swift:10 |
ConfigurationView |
ARKit-VisualFidelity/Views/ContentView.swift:11 |
ContentView |
ARKit-VisualFidelity/Views/ImmersiveView.swift:12 |
ImmersiveView |
ARKit-VisualFidelity/Views/StatusView.swift:11 |
StatusView |
ARKit-VisualFidelity/Views/ToggleMonitoringButton.swift:10 |
ToggleMonitoringButton |
ARKit-VisualFidelity/Views/ToggleVisualizationButton.swift:10 |
ToggleVisualizationButton |