Classifying Live Audio Input with a Built-in Sound Classifier

At a glance

Project structure

Source bundle/
├── ClassifySound/
│   ├── ClassifySoundApp.swift
│   ├── Support/
│   │   ├── ContentView.swift
│   │   ├── DetectSoundsView.swift
│   │   ├── SetupMonitoredSoundsView.swift
│   │   ├── ClassificationResultsSubject.swift
│   │   ├── DetectionState.swift
│   │   └── SoundIdentifier.swift
│   ├── SystemAudioClassifier.swift
│   └── Info.plist
├── ClassifySound.xcodeproj/
│   ├── .xcodesamplecode.plist
│   └── project.pbxproj
└── Configuration/
    └── SampleCode.xcconfig

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 4 project/configuration file(s) and 11 source declaration(s).

Overall architecture

flowchart LR
    N1["ClassifySoundApp"]
    N2["ContentView"]
    N3["SoundAnalysis APIs"]
    N1 --> N2
    N2 --> N3

Reference code

ClassifySound/ClassifySoundApp.swift:130 — architecture anchor

@main
struct ClassifySoundApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

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 Sound Analysis.

Ownership and state

classDiagram
    AppConfiguration *-- Double : inferenceWindowSize
    AppConfiguration *-- Double : overlapFactor
    AppConfiguration o-- Monitoredsounds : monitoredSounds
    AppState o-- AnyCancellable : detectionCancellable

Ownership evidence

ClassifySound/ClassifySoundApp.swift:15 — stored dependency or nearest verified ownership anchor

struct AppConfiguration {
    // ...
    var inferenceWindowSize = Double(1.5)
    // ...
}

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

ClassifySound/ClassifySoundApp.swift:131 — representative type boundary

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

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

ClassifySound/ClassifySoundApp.swift:52 — representative boundary

class AppState: ObservableObject {
    // ...
    private var detectionCancellable: AnyCancellable? = nil
    // ...
}

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: App: ClassifySoundApp; View: ContentView, DetectSoundsView, SetupMonitoredSoundsView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: listAllValidSoundIdentifiers, restartDetection, advanceDetectionStates, generateConfidenceMeterBarColors, cardify, generateMeter, generateLabeledMeter, generateMeterCard.
• Files: ClassifySound/ClassifySoundApp.swift, ClassifySound/Support/ContentView.swift, ClassifySound/Support/DetectSoundsView.swift, ClassifySound/Support/SetupMonitoredSoundsView.swift, ClassifySound/SystemAudioClassifier.swift, ClassifySound/Support/ClassificationResultsSubject.swift.

Architecture takeaways

• ClassifySoundApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, SoundAnalysis, AVFoundation 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.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation