Managing Audio with SiriKit

At a glance

Project structure

Source bundle/
├── ControlAudio/
│   ├── ControlAudio/
│   │   ├── AppDelegate.swift
│   │   ├── SceneDelegate.swift
│   │   ├── ViewController.swift
│   │   ├── AppIntentVocabulary.plist
│   │   └── Base.lproj/
│   │       └── LaunchScreen.storyboard
│   ├── ControlAudioShared/
│   │   ├── AppleMusicAPIController.swift
│   │   ├── AppleMusicAPIStructures.swift
│   │   └── MediaPlayerUtilities.swift
│   ├── ControlAudioExtension/
│   │   └── IntentHandler.swift
│   └── ControlAudio.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 10 project/configuration file(s) and 47 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["AppleMusicAPIController"]
    N3["IntentHandler"]
    N4["Intents APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

ControlAudio/ControlAudio/AppDelegate.swift:13 — architecture anchor

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

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 Intents.

Ownership and state

classDiagram
    AppDelegate o-- UIWindow : window
    AppDelegate o-- AppleMusicAPIController : appleMusicAPIController
    AppleMusicAPIController *-- String : storefront
    AppleMusicAPIController *-- String : userToken

Ownership evidence

ControlAudio/ControlAudio/AppDelegate.swift:16 — 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

ControlAudio/ControlAudio/AppDelegate.swift:30 — representative execution boundary

        DispatchQueue.global(qos: .userInitiated).async {
            let context = INMediaUserContext()
            // ...
        }

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

ControlAudio/ControlAudio/AppDelegate.swift:14 — representative type boundary

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

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

Access control

Reference code

ControlAudio/ControlAudio/ViewController.swift:12 — representative boundary

class ViewController: UIViewController {
    // ...
    @IBOutlet private weak var playPauseButton: UIButton?
    // ...
}

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: AppleMusicAPIController, ViewController; Delegate: AppDelegate, SceneDelegate; Handler: IntentHandler.
• Protocols: no local protocol declaration in the scanned source.
• Methods: application, handlePlayMediaIntent, domainForType, fetchUIImageForIdentifier, sharedDefaults, retrieveSavedUserToken, saveUserToken, prepareForRequests.
• Files: ControlAudio/ControlAudio/AppDelegate.swift, ControlAudio/ControlAudioShared/AppleMusicAPIController.swift, ControlAudio/ControlAudio/SceneDelegate.swift, ControlAudio/ControlAudio/ViewController.swift, ControlAudio/ControlAudioExtension/IntentHandler.swift, ControlAudio/ControlAudioShared/MediaPlayerUtilities.swift.

Architecture takeaways

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