Incorporating MIDI 2 into your apps

At a glance

Project structure

Source bundle/
└── UniversalMIDIPacket/
    ├── UMP Receiver/
    │   ├── MIDIReceiverApp.swift
    │   └── Views/
    │       └── PacketReceiverView.swift
    ├── UMP Send/
    │   ├── MIDISendApp.swift
    │   ├── Views/
    │   │   ├── Builder/
    │   │   │   └── PacketBuilderView.swift
    │   │   ├── Inspector/
    │   │   │   └── PacketChunkView.swift
    │   │   └── PacketSenderView.swift
    │   └── Models/
    │       ├── MIDIEndpointManager.swift
    │       └── PacketModel.swift
    └── Shared/
        ├── Models/
        │   ├── LogModel.swift
        │   └── MIDIEndpointModel.swift
        ├── Views/
        │   └── LogView.swift
        └── Realtime/
            └── MIDIAdapter.h

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Objective-C++, Swift.
• The verified tree contains 7 project/configuration file(s) and 35 source declaration(s).

Overall architecture

flowchart LR
    N1["MIDIReceiverApp"]
    N2["PacketReceiverView"]
    N3["MIDIEndpointManager"]
    N4["MIDIAdapter"]
    N5["CoreMIDI APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

UniversalMIDIPacket/UMP Receiver/MIDIReceiverApp.swift:10 — architecture anchor

@main
struct MIDIReceiverApp: App {

    private var appState = AppState()

    var body: some Scene {
        WindowGroup {
            PacketReceiverView(receiverOptions: appState.receiverOptions,
                               logModel: appState.logModel)
            .padding(EdgeInsets(top: 12.5, leading: 10.0, bottom: 25.0, trailing: 10.0))
            .onAppear {
                appState.receiverManager.startLogTimer()
            }
            .onDisappear {
                appState.receiverManager.stopLogTimer()
            }
        }
    }

}

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 Core MIDI.

Ownership and state

classDiagram
    MIDIReceiverApp *-- AppState : appState
    MIDIReceiver *-- AppState : appState
    PacketReceiverView o-- ReceiverOptions : receiverOptions
    PacketReceiverView o-- LogModel : logModel

Ownership evidence

UniversalMIDIPacket/UMP Receiver/MIDIReceiverApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct MIDIReceiverApp: App {
    // ...
    private var appState = AppState()
    // ...
}

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.

No source-visible execution, scheduling, or synchronization boundary was found in the indexed source.

@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.

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

UniversalMIDIPacket/UMP Receiver/MIDIReceiverApp.swift:11 — representative type boundary

@main
struct MIDIReceiverApp: App {
    // ...
    private var appState = AppState()
    // ...
}

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

Access control

Reference code

UniversalMIDIPacket/Shared/Extensions/MIDIEventPacketExtensions.swift:13 — representative boundary

    public var description: String {
        // ...
        case .noteOff:
        // ...
    }

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: Adapter: MIDIAdapter; App: MIDIReceiverApp; Manager: MIDIEndpointManager; Model: LogModel, MIDIEndpointModel, PacketModel; View: DestinationProtocolView, DestinationTextView, DynamicChunkView, LogView, MIDIDestinationView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: print, clear, populateDestinations.
• Files: UniversalMIDIPacket/UMP Receiver/MIDIReceiverApp.swift, UniversalMIDIPacket/UMP Receiver/Views/PacketReceiverView.swift, UniversalMIDIPacket/UMP Send/Views/Builder/PacketBuilderView.swift, UniversalMIDIPacket/UMP Send/Views/Inspector/PacketChunkView.swift, UniversalMIDIPacket/Shared/Models/LogModel.swift, UniversalMIDIPacket/Shared/Models/MIDIEndpointModel.swift.

Architecture takeaways

• MIDIReceiverApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, CoreMIDI, CoreGraphics 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