Deeper examples for DockKit integration covering service architecture, Vision framework integration, custom animations, multi-camera workflows, and production patterns.

Service Architecture
Vision Framework Integration
AVCaptureSession Integration
Multi-Subject Tracking Logic
Tracking, Events, and Availability Boundaries
Custom Motor Animations
SwiftUI Integration
Camera Control via Accessory Events
Error Handling
Testing Patterns

Service Architecture

Isolate DockKit interactions in a dedicated actor to keep motor control and tracking off the main thread:

import DockKit
import AVFoundation
import Spatial

actor DockControlService {
    private var accessory: DockAccessory?
    private var trackingMode: TrackingMode = .system

    enum TrackingMode {
        case system
        case custom
        case manual
    }

    func start() async throws {
        for await stateChange in try DockAccessoryManager.shared.accessoryStateChanges {
            switch stateChange.state {
            case .docked:
                guard let newAccessory = stateChange.accessory else { continue }
                accessory = newAccessory
                try await configureAccessory(newAccessory)
            case .undocked:
                accessory = nil
            @unknown default:
                break
            }
        }
    }

    private func configureAccessory(_ accessory: DockAccessory) async throws {
        try await DockAccessoryManager.shared.setSystemTrackingEnabled(true)
        trackingMode = .system
    }

    func setTrackingMode(_ mode: TrackingMode) async throws {
        trackingMode = mode
        let systemEnabled = mode == .system
        try await DockAccessoryManager.shared.setSystemTrackingEnabled(systemEnabled)
    }

    var isConnected: Bool {
        accessory != nil
    }
}

Separating Camera and Dock Concerns

Follow Apple's sample app pattern: define a CaptureService actor for AVFoundation and a DockControlService actor for DockKit. Connect them through a shared model or delegate protocol:

protocol CameraCaptureDelegate: AnyObject, Sendable {
    func switchCamera() async
    func startOrStopCapture() async
    func zoom(factor: Double) async
}

extension DockControlService {
    func subscribeToAccessoryEvents(
        _ accessory: DockAccessory,
        cameraDelegate: CameraCaptureDelegate
    ) {
        guard #available(iOS 17.4, *) else { return }
        Task {
            do {
                for await event in try accessory.accessoryEvents {
                    switch event {
                    case .cameraShutter:
                        await cameraDelegate.startOrStopCapture()
                    case .cameraFlip:
                        await cameraDelegate.switchCamera()
                    case .cameraZoom(factor: let factor):
                        await cameraDelegate.zoom(factor: factor)
                    case .button(id: _, pressed: _):
                        break
                    @unknown default:
                        break
                    }
                }
            } catch {
                // Handle accessory event subscription errors
            }
        }
    }
}

Vision Framework Integration

Hand Tracking

Track a hand pose using Vision and feed observations to DockKit:

import Vision
import DockKit
import AVFoundation

final class HandTrackingProcessor: NSObject,
    AVCaptureVideoDataOutputSampleBufferDelegate
{
    private let accessory: DockAccessory
    private let captureDevice: AVCaptureDevice

    init(accessory: DockAccessory, captureDevice: AVCaptureDevice) {
        self.accessory = accessory
        self.captureDevice = captureDevice
    }

    func captureOutput(
        _ output: AVCaptureOutput,
        didOutput sampleBuffer: CMSampleBuffer,
        from connection: AVCaptureConnection
    ) {
        guard let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
            return
        }

        let request = VNDetectHumanHandPoseRequest()
        let handler = VNImageRequestHandler(
            cvPixelBuffer: pixelBuffer,
            options: [:]
        )

        do {
            try handler.perform([request])
            guard let result = request.results?.first else { return }

            // Use the index finger tip as the tracking point
            let thumbTip = try result.recognizedPoint(.thumbTip)
            guard thumbTip.confidence > 0.5 else { return }

            let rect = CGRect(
                x: thumbTip.location.x - 0.05,
                y: thumbTip.location.y - 0.05,
                width: 0.1,
                height: 0.1
            )

            let observation = DockAccessory.Observation(
                identifier: 0,
                type: .object,
                rect: rect,
                faceYawAngle: nil
            )

            let cameraInfo = DockAccessory.CameraInformation(
                captureDevice: captureDevice.deviceType,
                cameraPosition: captureDevice.position,
                orientation: .corrected,
                cameraIntrinsics: nil,
                referenceDimensions: nil
            )

            Task {
                try await accessory.track(
                    [observation],
                    cameraInformation: cameraInfo
                )
            }
        } catch {
            // Handle Vision errors
        }
    }
}

Animal Body Detection

Track pets by detecting animal body poses:

func detectAnimal(
    in pixelBuffer: CVPixelBuffer,
    accessory: DockAccessory,
    device: AVCaptureDevice
) throws {
    let request = VNDetectAnimalBodyPoseRequest()
    let handler = VNImageRequestHandler(
        cvPixelBuffer: pixelBuffer,
        options: [:]
    )
    try handler.perform([request])

    guard let result = request.results?.first else { return }

    // Use the bounding box from the animal pose
    let allPoints = try result.recognizedPoints(.all)
    let validPoints = allPoints.values.filter { $0.confidence > 0.3 }
    guard !validPoints.isEmpty else { return }

    let xs = validPoints.map(\.location.x)
    let ys = validPoints.map(\.location.y)
    let minX = xs.min()!, maxX = xs.max()!
    let minY = ys.min()!, maxY = ys.max()!

    let rect = CGRect(
        x: minX, y: minY,
        width: maxX - minX, height: maxY - minY
    )

    let observation = DockAccessory.Observation(
        identifier: 1,
        type: .object,
        rect: rect,
        faceYawAngle: nil
    )

    let cameraInfo = DockAccessory.CameraInformation(
        captureDevice: device.deviceType,
        cameraPosition: device.position,
        orientation: .corrected,
        cameraIntrinsics: nil,
        referenceDimensions: nil
    )

    Task {
        try await accessory.track(
            [observation],
            cameraInformation: cameraInfo
        )
    }
}

Vision's coordinate system matches DockKit's (normalized, lower-left origin), so bounding boxes pass through without conversion.

AVCaptureSession Integration

Setting Up the Capture Pipeline

import AVFoundation
import DockKit

actor CaptureService {
    private let session = AVCaptureSession()
    private var currentDevice: AVCaptureDevice?
    private var videoOutput: AVCaptureVideoDataOutput?

    func configure() throws {
        session.beginConfiguration()
        defer { session.commitConfiguration() }

        session.sessionPreset = .high

        guard let camera = AVCaptureDevice.default(
            .builtInWideAngleCamera,
            for: .video,
            position: .front
        ) else {
            throw CaptureError.noCameraAvailable
        }

        let input = try AVCaptureDeviceInput(device: camera)
        guard session.canAddInput(input) else {
            throw CaptureError.cannotAddInput
        }
        session.addInput(input)
        currentDevice = camera

        let output = AVCaptureVideoDataOutput()
        output.alwaysDiscardsLateVideoFrames = true
        guard session.canAddOutput(output) else {
            throw CaptureError.cannotAddOutput
        }
        session.addOutput(output)
        videoOutput = output
    }

    func startRunning() {
        session.startRunning()
    }

    func stopRunning() {
        session.stopRunning()
    }

    enum CaptureError: Error {
        case noCameraAvailable
        case cannotAddInput
        case cannotAddOutput
    }
}

Providing Camera Information from Capture Device

extension CaptureService {
    func makeCameraInformation() -> DockAccessory.CameraInformation? {
        guard let device = currentDevice else { return nil }
        return DockAccessory.CameraInformation(
            captureDevice: device.deviceType,
            cameraPosition: device.position,
            orientation: .corrected,
            cameraIntrinsics: nil,
            referenceDimensions: nil
        )
    }
}

Multi-Subject Tracking Logic

Prioritizing by Saliency

func trackMostSalient(accessory: DockAccessory) async throws {
    guard #available(iOS 18.0, *) else { return }

    for await state in try accessory.trackingStates {
        // Find the subject with saliency rank 1 (most important)
        let primary = state.trackedSubjects.first { subject in
            switch subject {
            case .person(let person):
                return person.saliencyRank == 1
            case .object(let object):
                return object.saliencyRank == 1
            }
        }

        if let primary {
            let id: UUID
            switch primary {
            case .person(let person): id = person.identifier
            case .object(let object): id = object.identifier
            }
            try await accessory.selectSubjects([id])
        }
    }
}

Tracking Who Looks at Camera

func trackEngagedSubjects(accessory: DockAccessory) async throws {
    guard #available(iOS 18.0, *) else { return }

    for await state in try accessory.trackingStates {
        let engaged = state.trackedSubjects.compactMap { subject -> UUID? in
            guard case .person(let person) = subject,
                  let confidence = person.lookingAtCameraConfidence,
                  confidence > 0.7 else { return nil }
            return person.identifier
        }
        if !engaged.isEmpty {
            try await accessory.selectSubjects(engaged)
        }
    }
}

Converting Tracking Rects to View Coordinates

Tracked subject rectangles are in normalized coordinates. Convert to view space for drawing overlays:

import UIKit

func convertToViewSpace(
    normalizedRect: CGRect,
    viewSize: CGSize
) -> CGRect {
    // DockKit uses lower-left origin; UIKit uses upper-left
    let flippedY = 1.0 - normalizedRect.origin.y - normalizedRect.height
    return CGRect(
        x: normalizedRect.origin.x * viewSize.width,
        y: flippedY * viewSize.height,
        width: normalizedRect.width * viewSize.width,
        height: normalizedRect.height * viewSize.height
    )
}

Tracking, Events, and Availability Boundaries

Use availability checks around newer DockKit streams:

API	Availability	Notes
`accessoryEvents`	iOS 17.4+	Throwing async sequence; can throw `.notConnected` or `.notSupportedByDevice`
`trackingStates`	iOS 18+	Throwing async sequence; emits active tracking summaries
`batteryStates`	iOS 18+	Throwing async sequence; emits accessory battery summaries

TrackingState.trackedSubjects contains .person(TrackedPerson) and .object(TrackedObject). Person fields are identifier, rect, speakingConfidence, lookingAtCameraConfidence, and saliencyRank. Object fields are identifier, rect, and saliencyRank. Identifiers are random session identifiers and do not persist across tracking sessions.

Accessory event cases are:

Case	Use
`.cameraShutter`	Toggle capture or recording
`.cameraFlip`	Switch front/back camera
`.cameraZoom(factor:)`	Apply relative zoom intent
`.button(id:pressed:)`	Custom accessory button press/release

Custom Motor Animations

Sweep Animation

Create a horizontal sweep for panoramic capture:

func performSweep(accessory: DockAccessory) async throws {
    try await DockAccessoryManager.shared.setSystemTrackingEnabled(false)

    // Sweep right
    let rightVelocity = Vector3D(x: 0.0, y: 0.2, z: 0.0)
    try await accessory.setAngularVelocity(rightVelocity)
    try await Task.sleep(for: .seconds(3))

    // Sweep left
    let leftVelocity = Vector3D(x: 0.0, y: -0.2, z: 0.0)
    try await accessory.setAngularVelocity(leftVelocity)
    try await Task.sleep(for: .seconds(6))

    // Sweep back to center
    try await accessory.setAngularVelocity(rightVelocity)
    try await Task.sleep(for: .seconds(3))

    // Stop
    try await accessory.setAngularVelocity(Vector3D())
    try await DockAccessoryManager.shared.setSystemTrackingEnabled(true)
}

Timed Position Sequence

func lookAround(accessory: DockAccessory) async throws {
    try await DockAccessoryManager.shared.setSystemTrackingEnabled(false)

    let positions: [(yaw: Double, pitch: Double, duration: Double)] = [
        (yaw: -0.5, pitch: 0.0, duration: 1.5),
        (yaw: 0.5, pitch: 0.0, duration: 3.0),
        (yaw: 0.0, pitch: -0.2, duration: 1.5),
        (yaw: 0.0, pitch: 0.0, duration: 1.0),
    ]

    for pos in positions {
        let target = Vector3D(x: pos.pitch, y: pos.yaw, z: 0.0)
        let progress = try accessory.setOrientation(
            target,
            duration: .seconds(pos.duration),
            relative: false
        )
        while !progress.isFinished && !progress.isCancelled {
            try await Task.sleep(for: .milliseconds(100))
        }
    }

    try await DockAccessoryManager.shared.setSystemTrackingEnabled(true)
}

SwiftUI Integration

Dock Status View

import SwiftUI
import DockKit

@Observable
final class DockViewModel {
    var isConnected = false
    var accessoryName: String?
    var batteryName: String?
    var batteryLevel: Double?
    var isCharging = false
    var trackingMode: TrackingMode = .system

    enum TrackingMode: String, CaseIterable {
        case system = "System"
        case custom = "Custom"
        case manual = "Manual"
    }

    private var accessory: DockAccessory?

    func startObserving() {
        Task {
            do {
                for await stateChange in try DockAccessoryManager.shared.accessoryStateChanges {
                    await MainActor.run {
                        switch stateChange.state {
                        case .docked:
                            isConnected = true
                            accessory = stateChange.accessory
                            accessoryName = stateChange.accessory?.identifier.name
                        case .undocked:
                            isConnected = false
                            accessory = nil
                            accessoryName = nil
                            batteryName = nil
                            batteryLevel = nil
                        @unknown default:
                            break
                        }
                    }
                    if let acc = stateChange.accessory, stateChange.state == .docked {
                        observeBattery(acc)
                    }
                }
            } catch {
                // Handle error
            }
        }
    }

    private func observeBattery(_ accessory: DockAccessory) {
        guard #available(iOS 18.0, *) else { return }
        Task {
            do {
                for await battery in try accessory.batteryStates {
                    await MainActor.run {
                        batteryName = battery.name
                        batteryLevel = battery.batteryLevel
                        isCharging = battery.chargeState == .charging
                    }
                }
            } catch {
                // Handle error
            }
        }
    }

    func updateTrackingMode(_ mode: TrackingMode) {
        trackingMode = mode
        Task {
            try await DockAccessoryManager.shared.setSystemTrackingEnabled(
                mode == .system
            )
        }
    }
}

struct DockStatusView: View {
    @State private var viewModel = DockViewModel()

    var body: some View {
        VStack(alignment: .leading) {
            if viewModel.isConnected {
                Label(
                    viewModel.accessoryName ?? "DockKit Accessory",
                    systemImage: "dock.rectangle"
                )
                .font(.headline)

                if let level = viewModel.batteryLevel {
                    HStack {
                        Image(systemName: viewModel.isCharging
                              ? "battery.100percent.bolt"
                              : "battery.75percent")
                        Text("\(Int(level * 100))%")
                    }
                }

                Picker("Tracking", selection: $viewModel.trackingMode) {
                    ForEach(DockViewModel.TrackingMode.allCases, id: \.self) {
                        Text($0.rawValue)
                    }
                }
                .pickerStyle(.segmented)
                .onChange(of: viewModel.trackingMode) { _, newValue in
                    viewModel.updateTrackingMode(newValue)
                }
            } else {
                Label("No Dock Connected", systemImage: "dock.rectangle")
                    .foregroundStyle(.secondary)
            }
        }
        .task {
            viewModel.startObserving()
        }
    }
}

Manual Control Overlay

struct ManualControlView: View {
    let accessory: DockAccessory
    let speed: Double = 0.2

    var body: some View {
        VStack {
            Button { move(.tiltUp) } label: {
                Image(systemName: "chevron.up")
            }
            HStack {
                Button { move(.panLeft) } label: {
                    Image(systemName: "chevron.left")
                }
                Button { stop() } label: {
                    Image(systemName: "stop.fill")
                }
                Button { move(.panRight) } label: {
                    Image(systemName: "chevron.right")
                }
            }
            Button { move(.tiltDown) } label: {
                Image(systemName: "chevron.down")
            }
        }
        .font(.title)
    }

    enum Direction { case tiltUp, tiltDown, panLeft, panRight }

    private func move(_ direction: Direction) {
        Task {
            var velocity = Vector3D()
            switch direction {
            case .tiltUp:    velocity.x = -speed
            case .tiltDown:  velocity.x = speed
            case .panLeft:   velocity.y = -speed
            case .panRight:  velocity.y = speed
            }
            try await accessory.setAngularVelocity(velocity)
        }
    }

    private func stop() {
        Task {
            try await accessory.setAngularVelocity(Vector3D())
        }
    }
}

Camera Control via Accessory Events

Implementing Zoom

func handleZoom(factor: Double, device: AVCaptureDevice) {
    do {
        try device.lockForConfiguration()
        let direction = factor > 0 ? 1.0 : -1.0
        let scale = 0.2
        var newZoom = device.videoZoomFactor + direction * scale
        newZoom = max(
            min(newZoom, device.maxAvailableVideoZoomFactor),
            device.minAvailableVideoZoomFactor
        )
        device.videoZoomFactor = newZoom
        device.unlockForConfiguration()
    } catch {
        // Handle lock error
    }
}

Button-Triggered Panorama

func handlePanorama(
    accessory: DockAccessory,
    buttonID: Int,
    pressed: Bool
) async throws {
    guard buttonID == 5 else { return }

    if pressed {
        try await DockAccessoryManager.shared.setSystemTrackingEnabled(false)
        let velocity = Vector3D(x: 0.0, y: 0.15, z: 0.0)
        try await accessory.setAngularVelocity(velocity)
    } else {
        try await accessory.setAngularVelocity(Vector3D())
        try await DockAccessoryManager.shared.setSystemTrackingEnabled(true)
    }
}

Error Handling

DockKitError Cases

Error	Cause	Recovery
`.notConnected`	No accessory is docked	Wait for `.docked` state
`.notSupported`	Operation not available	Check framework availability
`.notSupportedByDevice`	Device lacks DockKit support	Degrade gracefully
`.invalidParameter`	Bad input value	Validate before calling
`.cameraTCCMissing`	Camera terms or authorization missing	Explain the camera access requirement
`.frameRateTooHigh`	`track()` exceeds 30 fps, or `animate` / `setOrientation` exceeds 2 calls per second	Reduce call frequency
`.frameRateTooLow`	Observations below 10 fps	Increase call frequency
`.noSubjectFound`	No trackable subject detected	Show user guidance

Guarding API Calls

func safeTrack(
    observations: [DockAccessory.Observation],
    cameraInfo: DockAccessory.CameraInformation,
    accessory: DockAccessory
) async {
    do {
        try await accessory.track(observations, cameraInformation: cameraInfo)
    } catch let error as DockKitError {
        switch error {
        case .notConnected:
            // Accessory disconnected, stop tracking loop
            break
        case .frameRateTooHigh:
            // Throttle observation delivery
            break
        case .frameRateTooLow:
            // Speed up frame processing
            break
        case .noSubjectFound:
            // No subject in observations, continue
            break
        default:
            break
        }
    } catch {
        // Unexpected error
    }
}

Testing Patterns

Conditional DockKit Integration

DockKit requires physical hardware. Use conditional compilation or runtime checks to keep the app functional without a dock:

#if canImport(DockKit)
import DockKit
#endif

final class DockController {
    var isDockKitAvailable: Bool {
        #if canImport(DockKit)
        return true
        #else
        return false
        #endif
    }

    func startTracking() async {
        #if canImport(DockKit)
        do {
            for await stateChange in try DockAccessoryManager.shared.accessoryStateChanges {
                // Handle state changes
            }
        } catch {
            // DockKit not available on this device
        }
        #endif
    }
}

Mock Accessory for UI Development

When building UI without hardware, mock the accessory state:

@Observable
final class MockDockViewModel {
    var isConnected = true
    var accessoryName: String? = "Mock DockKit Stand"
    var batteryLevel: Double? = 0.75
    var isCharging = false
    var trackingMode = "System"

    // Use in SwiftUI previews
    func simulateDisconnect() {
        isConnected = false
        accessoryName = nil
        batteryLevel = nil
    }
}

.tessl-plugin

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accessorysetupkit

activitykit

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app-clips

app-intents

app-store-optimization

app-store-review

apple-on-device-ai

appmigrationkit

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dockkit-patterns.md

SKILL.md

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weatherkit

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README.md

tile.json

dpearson2699/swift-ios-skills

dockkit-patterns.mdskills/dockkit/references/

DockKit Extended Patterns

Contents

Service Architecture

Separating Camera and Dock Concerns

Vision Framework Integration

Hand Tracking

Animal Body Detection

AVCaptureSession Integration

Setting Up the Capture Pipeline

Providing Camera Information from Capture Device

Multi-Subject Tracking Logic

Prioritizing by Saliency

Tracking Who Looks at Camera

Converting Tracking Rects to View Coordinates

Tracking, Events, and Availability Boundaries

Custom Motor Animations

Sweep Animation

Timed Position Sequence

SwiftUI Integration

Dock Status View

Manual Control Overlay

Camera Control via Accessory Events

Implementing Zoom

Button-Triggered Panorama

Error Handling

DockKitError Cases

Guarding API Calls

Testing Patterns

Conditional DockKit Integration

Mock Accessory for UI Development

dpearson2699/swift-ios-skills

dockkit-patterns.md.css-3qkkll{font-size:var(--chakra-font-sizes-sm);font-weight:var(--chakra-font-weights-normal);color:var(--chakra-colors-gray-300);}skills/dockkit/references/

DockKit Extended Patterns

Contents

Service Architecture

Separating Camera and Dock Concerns

Vision Framework Integration

Hand Tracking

Animal Body Detection

AVCaptureSession Integration

Setting Up the Capture Pipeline

Providing Camera Information from Capture Device

Multi-Subject Tracking Logic

Prioritizing by Saliency

Tracking Who Looks at Camera

Converting Tracking Rects to View Coordinates

Tracking, Events, and Availability Boundaries

Custom Motor Animations

Sweep Animation

Timed Position Sequence

SwiftUI Integration

Dock Status View

Manual Control Overlay

Camera Control via Accessory Events

Implementing Zoom

Button-Triggered Panorama

Error Handling

DockKitError Cases

Guarding API Calls

Testing Patterns

Conditional DockKit Integration

Mock Accessory for UI Development

dockkit-patterns.mdskills/dockkit/references/