Tracking and visualizing faces

At a glance

Project structure

Source bundle/
├── ARKitFaceExample/
│   ├── AppDelegate.swift
│   ├── ViewController.swift
│   ├── Face Overlay Content/
│   │   ├── VirtualContent.swift
│   │   ├── BlendShapeCharacter.swift
│   │   ├── FaceOcclusionOverlay.swift
│   │   ├── TexturedFace.swift
│   │   ├── TransformVisualization.swift
│   │   └── VideoTexturedFace.swift
│   ├── Utilities.swift
│   └── Base.lproj/
│       └── Main.storyboard
└── ARKitFaceExample.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 6 project/configuration file(s) and 9 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["ViewController"]
    N3["ARKit APIs"]
    N1 --> N2
    N2 --> N3

Reference code

ARKitFaceExample/AppDelegate.swift:11 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    // ...
}

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 ARKit.

Ownership and state

classDiagram
    AppDelegate o-- UIWindow : window
    ViewController o-- ARSCNView : sceneView
    ViewController o-- UITabBar : tabBar
    ViewController *-- Dictionary : faceAnchorsAndContentControllers

Ownership evidence

ARKitFaceExample/AppDelegate.swift:13 — stored dependency or nearest verified ownership anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    // ...
}

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.

Class and protocol design

ARKitFaceExample/Face Overlay Content/VirtualContent.swift:31 — representative type boundary

protocol VirtualContentController: ARSCNViewDelegate {
    // ...
}

The source explicitly defines local protocol relationships: BlendShapeCharacter → VirtualContentController, FaceOcclusionOverlay → VirtualContentController, TexturedFace → VirtualContentController, TransformVisualization → VirtualContentController.

Access control

Reference code

ARKitFaceExample/Face Overlay Content/BlendShapeCharacter.swift:17 — representative boundary

    private var originalJawY: Float = 0
    
    private lazy var jawNode = contentNode!.childNode(withName: "jaw", recursively: true)!
    private lazy var eyeLeftNode = contentNode!.childNode(withName: "eyeLeft", recursively: true)!
    private lazy var eyeRightNode = contentNode!.childNode(withName: "eyeRight", recursively: 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: Controller: ViewController, VirtualContentController; Delegate: AppDelegate.
• Protocols: VirtualContentController.
• Methods: application, viewDidLoad, viewDidAppear, session, resetTracking, displayErrorMessage, tabBar, renderer.
• Files: ARKitFaceExample/AppDelegate.swift, ARKitFaceExample/ViewController.swift, ARKitFaceExample/Face Overlay Content/BlendShapeCharacter.swift, ARKitFaceExample/Face Overlay Content/FaceOcclusionOverlay.swift, ARKitFaceExample/Face Overlay Content/TexturedFace.swift, ARKitFaceExample/Face Overlay Content/TransformVisualization.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches ARKit, SceneKit, UIKit 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.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation