Tracking geographic locations in AR

At a glance

Project structure

Source bundle/
├── GeoTrackingExample/
│   ├── AppDelegate.swift
│   ├── ViewController.swift
│   ├── Utilities.swift
│   ├── GPXParser.swift
│   ├── GPXExporter.swift
│   ├── GeoAnchorWithAssociatedData.swift
│   ├── ViewController+CoachingOverlay.swift
│   ├── ViewController+LoadSaveAnchors.swift
│   └── Base.lproj/
│       └── LaunchScreen.storyboard
├── Configuration/
│   └── SampleCode.xcconfig
└── GeoTrackingExample.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 7 source declaration(s).

Overall architecture

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

Reference code

GeoTrackingExample/AppDelegate.swift:11 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        /* Check whether the device supports geotracking. Present
         an error-message view controller, if not. */
        if !ARGeoTrackingConfiguration.isSupported {
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            window?.rootViewController = storyboard.instantiateViewController(withIdentifier: "unsupportedDeviceMessage")
        }
        return true
    }

    func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool {
        if let viewController = self.window?.rootViewController as? ViewController {
            viewController.parseGPXFile(with: url)
            return true
        } else {
            return false
        }
    }
}

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-- ARView : arView
    ViewController o-- MKMapView : mapView
    ViewController o-- UILabel : toastLabel

Ownership evidence

GeoTrackingExample/AppDelegate.swift:14 — 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.

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

GeoTrackingExample/Utilities.swift:63 — representative execution boundary

        DispatchQueue.main.asyncAfter(deadline: .now() + delay) {
            var transform: Transform = .identity
            transform.translation = self.transform.translation + translation
            transform.scale = self.transform.scale * scale
            self.move(to: transform, relativeTo: self.parent, duration: duration, timingFunction: .easeInOut)
        }

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

GeoTrackingExample/GPXParser.swift:10 — representative type boundary

protocol GPXParserDelegate: AnyObject {
    func parser(_ parser: GPXParser, didFinishParsingFileWithAnchors anchors: [ARGeoAnchor])
}

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

Access control

Reference code

GeoTrackingExample/GPXExporter.swift:14 — representative boundary

class GPXExporter {
    // ...
    private let gpxPrefix = """
    <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
    <gpx xmlns="http://www.topografix.com/GPX/1/1" creator="Apple Inc.">

    """
    // ...
}

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; Delegate: AppDelegate, GPXParserDelegate.
• Protocols: GPXParserDelegate.
• Methods: application, viewDidLoad, viewDidAppear, viewDidDisappear, menuButtonTapped, handleTapOnARView, handleTapOnMapView, undoButtonTapped.
• Files: GeoTrackingExample/AppDelegate.swift, GeoTrackingExample/ViewController.swift, GeoTrackingExample/GPXParser.swift, GeoTrackingExample/GPXExporter.swift, GeoTrackingExample/GeoAnchorWithAssociatedData.swift.

Architecture takeaways

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