accessorysetupkit

Guidance for adopting AccessorySetupKit, Apple's privacy-preserving discovery and setup layer for Bluetooth and Wi-Fi accessories on iOS 18+ / Swift 6.3. Instead of broad Bluetooth or Wi-Fi permission prompts, it presents a system-provided picker that grants per-accessory access with a single tap; after setup, apps continue communicating through CoreBluetooth or NetworkExtension, with AccessorySetupKit handling only discovery and authorization.

Setup begins with Info.plist keys: NSAccessorySetupSupports listing Bluetooth and/or WiFi, plus Bluetooth-specific keys for service UUIDs, names or substrings, and two-byte company identifiers. These must match the discovery descriptor or the app crashes during discovery. A notable benefit is that once NSAccessorySetupSupports declares Bluetooth, creating a CBCentralManager no longer triggers the system permission dialog, and central state reaches poweredOn only when at least one accessory is paired.

ASDiscoveryDescriptor defines matching criteria. Bluetooth descriptors need at least a company identifier or service UUID, with optional narrower matchers (name substring, manufacturer or service data blob plus an equal-length mask) and a bluetoothRange of default or immediate. Wi-Fi descriptors take either ssid or ssidPrefix but never both, and supportedOptions declare capabilities such as bluetoothPairingLE, bluetoothTransportBridging, or bluetoothHID.

Discovery is driven by ASAccessorySession: activate it, wait for the activated event before reading session.accessories or showing the picker, then handle events like accessoryAdded, accessoryChanged, accessoryRemoved, invalidated, migrationComplete, and picker presentation events. The picker is populated with ASPickerDisplayItem instances (name, product image, descriptor), runs in a separate system process, and shows multiple matches as a carousel. Per-item setupOptions (rename, confirmAuthorization, finishInApp), product-image best practices for the 180x120 point container, and migration from CoreBluetooth permission-based scanning round out the coverage.