Incorporating Audio Effects and Instruments

At a glance

Project structure

Source bundle/
├── Shared/
│   ├── AudioUnitManager.swift
│   └── Support/
│       ├── SimplePlayEngine.swift
│       └── ViewExtensions.swift
├── macOS/
│   └── AUv3Host/
│       ├── MainViewController.swift
│       ├── AppDelegate.swift
│       ├── ComponentViewController.swift
│       ├── ListViewController.swift
│       ├── PresetsViewController.swift
│       ├── SaveSheetViewController.swift
│       └── AlertExtensions.swift
└── iOS/
    └── AUv3Host/
        ├── AppDelegate.swift
        └── MainViewController.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 8 project/configuration file(s) and 22 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["iOS"]
    V2["macOS"]
    Boundary["Cocoa / UIKit APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

iOS/AUv3Host/AppDelegate.swift:10 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

}

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    UserPresetsChange o-- UserPresetsChangeType : type
    UserPresetsChange *-- Array : userPresets
    UserPresetsChange o-- Notification : userPresetsChanged
    Preset o-- AUAudioUnitPreset : audioUnitPreset

Ownership evidence

Shared/AudioUnitManager.swift:45 — stored dependency or nearest verified ownership anchor

struct UserPresetsChange {
    let type: UserPresetsChangeType
    let userPresets: [Preset]
}

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

Shared/AudioUnitManager.swift:141 — representative execution boundary

                DispatchQueue.main.async {
                    var changeType = self.userPresetChangeType
                    // ...
                }

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

macOS/AUv3Host/MainViewController.swift:10 — representative type boundary

protocol Coordinator: AnyObject {
    // ...
    func didSelectPreset(_ preset: Preset)
    // ...
}

The source explicitly defines local protocol relationships: MainViewController → Coordinator.

Access control

Reference code

Shared/AudioUnitManager.swift:61 — representative boundary

    fileprivate init(preset: AUAudioUnitPreset) {
        audioUnitPreset = preset
    }

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: Component: Component; Controller: ComponentViewController, ListViewController, MainViewController, PresetsViewController, SaveSheetViewController; Coordinator: Coordinator; Delegate: AppDelegate; Engine: SimplePlayEngine; Manager: AudioUnitManager; Player: InstrumentPlayer; View: BarView, SplitView.
• Protocols: Coordinator.
• Methods: requestGenericViewController, requestViewController, savePreset, deletePreset, toggleViewMode, loadAudioUnits, selectComponent, loadAudioUnitViewController.
• Files: Shared/AudioUnitManager.swift, macOS/AUv3Host/MainViewController.swift, iOS/AUv3Host/AppDelegate.swift, macOS/AUv3Host/AppDelegate.swift, Shared/Support/SimplePlayEngine.swift, iOS/AUv3Host/MainViewController.swift.

Architecture takeaways

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