Core Bluetooth serves as Apple's primary framework for integrating Bluetooth Low Energy (BLE) functionality into iOS and macOS applications. This tutorial explores the foundational concepts of Core Bluetooth by guiding readers through building a chat app while delving into BLE, which supports energy-efficient communication with low-powered devices. Core Bluetooth operates on a server/client model, where devices are classified as centrals or peripherals based on their roles in communication, and services and characteristics are crucial elements in organizing device capabilities. Since iOS 13, Core Bluetooth has expanded its support to classic Bluetooth devices, broadening the scope of wireless devices accessible to third-party apps. Despite its potential, developing with Core Bluetooth is complex, requiring careful navigation through multiple steps to establish connections between devices and robust error handling due to potential instabilities and security concerns. The tutorial also highlights challenges faced during app development, such as deciding device roles and dealing with message size limitations, while recommending Ditto’s synchronization technology for easier integration of local communication features.