Communicating between a DriverKit extension and a client app

At a glance

Project structure

Source bundle/
└── DriverKitUserClientSample/
    ├── DriverKitSampleApp/
    │   ├── DriverKitSampleApp.swift
    │   ├── DriverCommunicationViewModel.swift
    │   ├── DriverCommunicationView.swift
    │   ├── DriverKitSampleView.swift
    │   ├── DriverLoadingViewModel+macOS.swift
    │   ├── DriverLoadingView+iOS.swift
    │   ├── DriverLoadingView+macOS.swift
    │   ├── DriverKitSampleApp-Bridging-Header.h
    │   ├── UserClientCommunication.c
    │   └── UserClientCommunication.h
    └── NullDriver/
        ├── NullDriverUserClient.cpp
        └── NullDriver.cpp

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C, C++, C/Objective-C header, Swift.
• The verified tree contains 7 project/configuration file(s) and 16 source declaration(s).

Overall architecture

flowchart LR
    N1["DriverKitSampleApp"]
    N2["DriverKitSampleView"]
    N3["DriverCommunicationViewModel"]
    N4["DriverKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

DriverKitUserClientSample/DriverKitSampleApp/DriverKitSampleApp.swift:10 — architecture anchor

@main
struct DriverKitSampleApp: App {
    var body: some Scene {
        WindowGroup {
            DriverKitSampleView()
        }
    }
}

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 DriverKit.

Ownership and state

classDiagram
    DriverCommunicationViewModel *-- Bool : isConnected
    DriverCommunicationViewModel o-- io_connect_t : connection
    DriverCommunicationViewModel *-- UnsafeMutableRawPointer : opaqueSelf
    DriverCommunicationViewModel o-- State : state

Ownership evidence

DriverKitUserClientSample/DriverKitSampleApp/DriverCommunicationViewModel.swift:66 — stored dependency or nearest verified ownership anchor

class DriverCommunicationViewModel: NSObject, ObservableObject {
    // ...
    @Published public var isConnected: Bool = false
    // ...
}

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

DriverKitUserClientSample/DriverKitSampleApp/DriverLoadingViewModel+macOS.swift:226 — representative execution boundary

#if swift(>=5.5)
        DispatchQueue.main.async {
            self.state = DriverLoadingStateMachine.process(self.state, self.installedDextProperties != nil ? .discoveredLoaded : .discoveredUnloaded)
        }
#endif

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

DriverKitUserClientSample/DriverKitSampleApp/DriverKitSampleApp.swift:11 — representative type boundary

@main
struct DriverKitSampleApp: App {
    // ...
            DriverKitSampleView()
    // ...
}

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

Access control

Reference code

DriverKitUserClientSample/DriverKitSampleApp/DriverCommunicationView.swift:13 — representative boundary

    @Binding var displayedView: DriverKitSampleView.DisplayedView
    @ObservedObject public var viewModel: DriverCommunicationViewModel = .init()

    var body: some View {
        // ...
    }

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: DriverKitSampleApp; View: DisplayedView, DriverCommunicationView, DriverKitSampleView, DriverLoadingView; ViewModel: DriverCommunicationViewModel, DriverLoadingViewModel.
• Protocols: no local protocol declaration in the scanned source.
• Methods: SwiftAsyncCallback, SwiftDeviceAdded, SwiftDeviceRemoved, process, LocalAsyncCallback, ProcessResult, SwiftUncheckedScalar, SwiftUncheckedStruct.
• Files: DriverKitUserClientSample/DriverKitSampleApp/DriverKitSampleApp.swift, DriverKitUserClientSample/DriverKitSampleApp/DriverCommunicationViewModel.swift, DriverKitUserClientSample/DriverKitSampleApp/DriverCommunicationView.swift, DriverKitUserClientSample/DriverKitSampleApp/DriverKitSampleView.swift.

Architecture takeaways

• DriverKitSampleApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches DriverKit, SwiftUI, IOKit, CoreFoundation 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