homekit

HomeKit

Control home automation accessories and commission Matter devices. HomeKit manages the home/room/accessory model, action sets, and triggers. MatterSupport handles device commissioning into your ecosystem.

Contents

• Setup
• HomeKit Data Model
• Managing Accessories
• Reading and Writing Characteristics
• Action Sets and Triggers
• Matter Commissioning
• MatterAddDeviceExtensionRequestHandler
• Common Mistakes
• Review Checklist
• References

Setup

HomeKit Configuration

1. Enable the HomeKit capability in Xcode (Signing & Capabilities)
2. Add NSHomeKitUsageDescription to Info.plist:

<key>NSHomeKitUsageDescription</key>
<string>This app controls your smart home accessories.</string>

MatterSupport Configuration

For Matter commissioning into your own ecosystem:

1. Add a MatterSupport Extension target and set its principal class to a MatterAddDeviceExtensionRequestHandler subclass
2. Add NSBonjourServices entries for _matter._tcp, _matterc._udp, and _matterd._udp
3. Add com.apple.developer.matter.allow-setup-payload only if the caller supplies a Matter setup payload programmatically

Framework Boundary

Need	Framework
Homes, rooms, accessories, characteristics, actions, triggers	HomeKit
Commission Matter into the app ecosystem	MatterSupport
Select and authorize a nearby Bluetooth or Wi-Fi accessory	AccessorySetupKit
Exchange Bluetooth GATT data after selection	CoreBluetooth
Join or configure an accessory's Wi-Fi network after selection	NetworkExtension

HomeKit Data Model

HomeKit organizes home automation in a hierarchy:

HMHomeManager
  -> HMHome (one or more)
       -> HMRoom (rooms in the home)
            -> HMAccessory (devices in a room)
                 -> HMService (functions: light, thermostat, etc.)
                      -> HMCharacteristic (readable/writable values)
       -> HMZone (groups of rooms)
       -> HMActionSet (grouped actions)
       -> HMTrigger (time or event-based triggers)

Initializing the Home Manager

Create a single HMHomeManager and implement the delegate to know when data is loaded. HomeKit loads asynchronously -- do not access homes until the delegate fires.

import HomeKit

final class HomeStore: NSObject, HMHomeManagerDelegate {
    let homeManager = HMHomeManager()

    override init() {
        super.init()
        homeManager.delegate = self
    }

    func homeManagerDidUpdateHomes(_ manager: HMHomeManager) {
        // Safe to access manager.homes now
        let homes = manager.homes
        let primaryHome = manager.primaryHome
        print("Loaded \(homes.count) homes")
    }

    func homeManager(
        _ manager: HMHomeManager,
        didUpdate status: HMHomeManagerAuthorizationStatus
    ) {
        if status.contains(.authorized) {
            print("HomeKit access granted")
        }
    }
}

Accessing Rooms

guard let home = homeManager.primaryHome else { return }

let rooms = home.rooms
let kitchen = rooms.first { $0.name == "Kitchen" }

// Room for accessories not assigned to a specific room
let defaultRoom = home.roomForEntireHome()

Managing Accessories

Discovering and Adding Accessories

Use the Framework Boundary table before adding an accessory; only HomeKit/MatterSupport work continues in this skill.

// System UI for accessory discovery
home.addAndSetupAccessories { error in
    if let error {
        print("Setup failed: \(error)")
    }
}

Listing Accessories and Services

for accessory in home.accessories {
    print("\(accessory.name) in \(accessory.room?.name ?? "unassigned")")

    for service in accessory.services {
        print("  Service: \(service.serviceType)")

        for characteristic in service.characteristics {
            print("    \(characteristic.characteristicType): \(characteristic.value ?? "nil")")
        }
    }
}

Moving an Accessory to a Room

guard let accessory = home.accessories.first,
      let bedroom = home.rooms.first(where: { $0.name == "Bedroom" }) else { return }

home.assignAccessory(accessory, to: bedroom) { error in
    if let error {
        print("Failed to move accessory: \(error)")
    }
}

Reading and Writing Characteristics

Reading a Value

let characteristic: HMCharacteristic = // obtained from a service

characteristic.readValue { error in
    guard error == nil else { return }
    if let value = characteristic.value as? Bool {
        print("Power state: \(value)")
    }
}

Writing a Value

// Turn on a light
characteristic.writeValue(true) { error in
    if let error {
        print("Write failed: \(error)")
    }
}

Observing Changes

Enable notifications for real-time updates:

characteristic.enableNotification(true) { error in
    guard error == nil else { return }
}

// In HMAccessoryDelegate:
func accessory(
    _ accessory: HMAccessory,
    service: HMService,
    didUpdateValueFor characteristic: HMCharacteristic
) {
    print("Updated: \(characteristic.value ?? "nil")")
}

Action Sets and Triggers

Creating an Action Set

An HMActionSet groups characteristic writes that execute together:

home.addActionSet(withName: "Good Night") { actionSet, error in
    guard let actionSet, error == nil else { return }

    // Turn off living room light
    let lightChar = livingRoomLight.powerCharacteristic
    let action = HMCharacteristicWriteAction(
        characteristic: lightChar,
        targetValue: false as NSCopying
    )
    actionSet.addAction(action) { error in
        guard error == nil else { return }
        print("Action added to Good Night scene")
    }
}

Executing an Action Set

home.executeActionSet(actionSet) { error in
    if let error {
        print("Execution failed: \(error)")
    }
}

Creating a Timer Trigger

var timeOfDay = DateComponents()
timeOfDay.hour = 22
timeOfDay.minute = 30

let firstFireDate = Calendar.current.nextDate(
    after: Date(),
    matching: timeOfDay,
    matchingPolicy: .nextTime
)!

let trigger = HMTimerTrigger(
    name: "Nightly",
    fireDate: firstFireDate,
    recurrence: DateComponents(day: 1)  // Repeat every day after firstFireDate
)

home.addTrigger(trigger) { error in
    guard error == nil else { return }

    // Attach the action set to the trigger
    trigger.addActionSet(goodNightActionSet) { error in
        guard error == nil else { return }

        trigger.enable(true) { error in
            print("Trigger enabled: \(error == nil)")
        }
    }
}

Creating an Event Trigger

let motionDetected = HMCharacteristicEvent(
    characteristic: motionSensorCharacteristic,
    triggerValue: true as NSCopying
)

let eventTrigger = HMEventTrigger(
    name: "Motion Lights",
    events: [motionDetected],
    predicate: nil
)

home.addTrigger(eventTrigger) { error in
    // Add action sets as above
}

Matter Commissioning

Use MatterAddDeviceRequest to commission a Matter device into your ecosystem. This is separate from the HMHome home-automation model; it handles the Matter setup flow and calls into your MatterSupport extension.

Basic Commissioning

import MatterSupport

func addMatterDevice() async throws {
    guard MatterAddDeviceRequest.isSupported else {
        print("Matter not supported on this device")
        return
    }

    let topology = MatterAddDeviceRequest.Topology(
        ecosystemName: "My Smart Home",
        homes: [
            MatterAddDeviceRequest.Home(displayName: "Main House")
        ]
    )

    let request = MatterAddDeviceRequest(
        topology: topology,
        setupPayload: nil,
        showing: .allDevices
    )

    // Presents system UI for device pairing
    try await request.perform()
}

When providing a setup code directly, import Matter and pass an MTRSetupPayload as setupPayload; this is the case that requires the setup-payload entitlement.

Filtering Devices

// Only show devices from a specific vendor
let criteria = MatterAddDeviceRequest.DeviceCriteria.vendorID(0x1234)

let request = MatterAddDeviceRequest(
    topology: topology,
    setupPayload: nil,
    showing: criteria
)

Combine criteria with .all([.vendorID(...), .not(.productID(...))]) or use .any(...) when any one criterion is enough.

MatterAddDeviceExtensionRequestHandler

For full ecosystem support, create a MatterSupport Extension. The extension handles commissioning callbacks. Override the needed methods, but do not call super from those overrides. Load the complete Advanced Matter Extension Handler for credential validation, room selection, configuration, commissioning, and network-association overrides.

Common Mistakes

Mistake	Fix
Reading homes before the delegate update	Create one manager, set its delegate, and wait for homeManagerDidUpdateHomes.
HomeKit setup is used for Matter ecosystem commissioning	Use MatterAddDeviceRequest plus the configured MatterSupport extension.
Matter configuration is incomplete	Verify principal handler, Bonjour services, and the setup-payload entitlement only when applicable.
Multiple HMHomeManager instances load the database	Share one retained manager/store.
Characteristic write ignores metadata	Check permissions, format, min/max/step, and allowed values before writing.

Review Checklist

• HomeKit capability enabled in Xcode
• NSHomeKitUsageDescription present in Info.plist
• Single HMHomeManager instance shared across the app
• HMHomeManagerDelegate implemented; homes not accessed before homeManagerDidUpdateHomes
• HMHomeDelegate set on homes to receive accessory and room changes
• HMAccessoryDelegate set on accessories to receive characteristic updates
• Characteristic metadata checked before writing values
• Error handling in all completion handlers
• MatterSupport extension target and principal handler configured
• Matter discovery NSBonjourServices entries added
• com.apple.developer.matter.allow-setup-payload used only when providing setup codes
• MatterAddDeviceRequest.isSupported checked before performing requests
• Matter extension handler implements commissionDevice(in:onboardingPayload:commissioningID:)
• Action sets tested with the HomeKit Accessory Simulator before shipping
• Triggers enabled after creation (trigger.enable(true))

References

• Extended patterns (Matter extension, delegate wiring, SwiftUI): references/matter-commissioning.md
• HomeKit framework
• HMHomeManager
• HMHome
• HMAccessory
• HMRoom
• HMActionSet
• HMTrigger
• MatterSupport framework
• MatterAddDeviceRequest
• MatterAddDeviceExtensionRequestHandler
• Enabling HomeKit in your app
• Adding Matter support to your ecosystem