Placing objects and handling 3D interaction

At a glance

Project structure

Source bundle/
└── ARKitInteraction/
    ├── AppDelegate.swift
    ├── Additional View Controllers/
    │   ├── StatusViewController.swift
    │   └── VirtualObjectSelection.swift
    ├── Focus Square/
    │   ├── FocusSquareSegment.swift
    │   └── FocusSquare.swift
    ├── ViewController.swift
    ├── Virtual Objects/
    │   ├── VirtualObjectLoader.swift
    │   └── VirtualObject.swift
    ├── VirtualObjectARView.swift
    ├── ViewController+ARSCNViewDelegate.swift
    ├── ThresholdPanGesture.swift
    └── ViewController+Actions.swift

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 19 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["StatusViewController"]
    N3["VirtualObjectLoader"]
    N4["ARKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

ARKitInteraction/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
    StatusViewController *-- Array : all
    StatusViewController o-- Callback : restartExperienceHandler
    StatusViewController o-- TimeInterval : displayDuration

Ownership evidence

ARKitInteraction/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

ARKitInteraction/Additional View Controllers/VirtualObjectSelection.swift:31 — representative type boundary

protocol VirtualObjectSelectionViewControllerDelegate: AnyObject {
    func virtualObjectSelectionViewController(_ selectionViewController: VirtualObjectSelectionViewController, didSelectObject: VirtualObject)
    func virtualObjectSelectionViewController(_ selectionViewController: VirtualObjectSelectionViewController, didDeselectObject: VirtualObject)
}

The source explicitly defines local protocol relationships: ViewController → VirtualObjectSelectionViewControllerDelegate.

Access control

Reference code

ARKitInteraction/Additional View Controllers/StatusViewController.swift:47 — representative boundary

    private let displayDuration: TimeInterval = 6
    
    // Timer for hiding messages.
    private var messageHideTimer: Timer?
    
    private var timers: [MessageType: Timer] = [:]

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: StatusViewController, ViewController, VirtualObjectSelectionViewController; Delegate: AppDelegate, VirtualObjectSelectionViewControllerDelegate; Loader: VirtualObjectLoader; View: VirtualObjectARView.
• Protocols: VirtualObjectSelectionViewControllerDelegate.
• Methods: application, applicationWillResignActive, applicationDidBecomeActive, showMessage, scheduleMessage, cancelScheduledMessage, cancelAllScheduledMessages, showTrackingQualityInfo.
• Files: ARKitInteraction/AppDelegate.swift, ARKitInteraction/Additional View Controllers/StatusViewController.swift, ARKitInteraction/ViewController.swift, ARKitInteraction/Virtual Objects/VirtualObjectLoader.swift, ARKitInteraction/VirtualObjectARView.swift, ARKitInteraction/Focus Square/FocusSquare.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches ARKit, UIKit, SceneKit 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