Artur Gurgul - BLE in the Apple ecosystem — iBeacon, ASK, UWB, Find My

ble · memo

In one line: Apple’s proximity features are different frameworks on the same radio: iBeacon is a BLE advert read by Core Location (not CoreBluetooth); AccessorySetupKit (iOS 18) pairs one accessory without the broad Bluetooth permission; Nearby Interaction measures distance + direction over UWB after BLE hands over tokens; Find My is a crowd relay of encrypted locations keyed by rotating BLE keys. Plain BLE GATT needs no MFi.

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BLE in the Apple ecosystem — iBeacon, ASK, UWB, Find My — figure 1

How it works

iBeacon = Core Location. CLBeaconRegion + CLBeaconIdentityConstraint(uuid:major:minor:) (iOS 13; iOS 17: CLMonitor). Monitoring = enter/exit, OS-level, relaunches a terminated app (needs Always); max 20 regions per app, geofences included. Ranging = startRangingBeacons(satisfying:), foreground: proximity .immediate/.near/.far + accuracy (m, from RSSI). CoreBluetooth hides iBeacon adverts. Sending one: peripheralData(withMeasuredPower:) → CBPeripheralManager, foreground only.
AccessorySetupKit (iOS 18) — ASAccessorySession .showPicker(for:) with ASPickerDisplayItem (name, image, ASDiscoveryDescriptor: service UUID / company id / name). The system scans and shows the sheet; the app gets an ASAccessory (bluetoothIdentifier) and uses CoreBluetooth for that accessory only — no global Bluetooth prompt. Info.plist: NSAccessorySetupKitSupports + descriptors.
Nearby Interaction (iOS 14) — U1 (iPhone 11–14) / U2 (iPhone 15+), AirTag, some Watches; both sides need UWB. Tokens are NSSecureCoding: archive, send, NINearbyPeerConfiguration(peerToken:). Third-party UWB chips: NINearbyAccessoryConfiguration (iOS 15). Check NISession.deviceCapabilities (iOS 16) — direction may be missing. Foreground-oriented; a paused session needs fresh tokens.
Find My network — third-party trackers join through the MFi Find My network accessory program (Apple’s spec). No public app API to read other people’s reports.
MFi — only for ExternalAccessory (iAP2 over Classic BT / Lightning / USB, UISupportedExternalAccessoryProtocols), Find My and similar programs. A BLE GATT peripheral (our ESP32s) needs none.
Beyond BLE — MultipeerConnectivity (MCSession: Wi-Fi, peer-to-peer Wi-Fi, Bluetooth; local-network usage string + NSBonjourServices); Wi-Fi Aware (iOS 26). HomeKit: entitlement + usage string; Matter (iOS 16.1+): MatterSupport, CSA-certified devices.

Remember

Beacon = Location, Accessory = ASK then CB, Precise = UWB after BLE, Lost = Find My relay, MFi = Classic/Find My only.

Which framework, what it needs

Job	Framework	Needs
GATT to a peripheral	CoreBluetooth	Bluetooth usage string; background modes
detect iBeacon	Core Location	location auth (Always to relaunch); no BT prompt
be an iBeacon	CL payload + CB	BT permission, app in foreground
onboard 1 accessory	AccessorySetupKit	iOS 18, Info.plist descriptors; then CB
distance + direction	NearbyInteraction	UWB both sides, NI usage string, a token channel
lost-item relay	Find My network	MFi program; hardware
classic / Lightning	ExternalAccessory	MFi + protocol strings

Example

let c = CLBeaconIdentityConstraint(uuid: hubUUID, major: 1)
let region = CLBeaconRegion(beaconIdentityConstraint: c,
                            identifier: "hub")
manager.requestAlwaysAuthorization()  // relaunch on entry
manager.startMonitoring(for: region)  // background, 20 max
func locationManager(_ m: CLLocationManager,
                     didEnterRegion r: CLRegion) {
  m.startRangingBeacons(satisfying: c) } // detail, fg
// UWB: my token out, the peer's token in, over GATT
let blob = try NSKeyedArchiver.archivedData(
  withRootObject: ni.discoveryToken!, requiringSecureCoding: true)
ni.run(NINearbyPeerConfiguration(peerToken: peerToken))

Interview traps

Ranging iBeacons with CBCentralManager — Core Location’s job; CB hides them.
“iBeacon gives me distance” — RSSI buckets, metres of error. Precision = UWB.
Ranging in the background — monitoring only; ranging is foreground.
“ASK replaces CoreBluetooth” — it replaces discovery + permission; GATT is still CoreBluetooth.
UWB without a side channel — it has no discovery; tokens travel over BLE/network.
“MFi for my BLE sensor” — no. And an iOS advert in the background drops the name and moves all service UUIDs to the overflow area.

Likely questions

Wake an app near a hub? — beacon region monitoring (Always).
Onboard without the BT prompt? — AccessorySetupKit.
Find My privacy? — rotating keys; encrypted to the owner.