corebluetooth_skill

Overview

This skill documents Apple Core Bluetooth for building BLE and Bluetooth Classic features across Apple platforms using Swift. It summarizes central and peripheral workflows, background processing and state restoration rules, GATT operations, and L2CAP usage. The content focuses on practical checklists, common pitfalls, and mapping to Core Bluetooth APIs.

How this skill works

The skill explains how to create and manage CBCentralManager and CBPeripheralManager instances, wait for .poweredOn state, and perform scanning, connecting, advertising, and GATT discovery. It guides readers through handling delegates, retaining peripheral objects, subscribing to notifications, reading/writing characteristics, and choosing L2CAP when GATT is insufficient. It also covers background modes and state restoration behaviors for reliable lifecycle handling.

When to use it

• When implementing a BLE central to discover and connect to remote peripherals.
• When implementing a local peripheral to advertise services and accept central connections.
• When you need reliable background scanning, connection restoration, or state preservation.
• When streaming data via notifications or using write-without-response for low-latency transfers.
• When L2CAP channels are required for custom high-throughput or non-GATT data flows.

Best practices

• Gate all BLE operations on manager state .poweredOn and implement centralManagerDidUpdateState(_:).
• Retain discovered CBPeripheral instances to avoid unexpected deallocation and lost connections.
• Stop scanning as soon as the target peripheral is found to conserve power and CPU.
• Set delegates early, discover services/characteristics in order, and handle asynchronous callbacks robustly.
• Use notifications for streaming, write-without-response only when canSendWriteWithoutResponse is true.
• Follow platform rules for background modes and implement state restoration to recover sessions.

Example use cases

• A fitness app acting as a central to read heart rate and battery characteristics from strap sensors.
• A hardware companion app advertising a custom service while acting as a peripheral for nearby controllers.
• A background location tracker that restores BLE connections after an app relaunch.
• A streaming audio or sensor pipeline using notifications for continuous data delivery.
• A custom high-throughput link using L2CAP channels for non-GATT binary transport.