The Core Bluetooth (CB) framework provides the resources your iOS apps need to communicate with devices that are equipped with Bluetooth low energy (BTLE) technology. This framework provides various classes to communicate with the Bluetooth devices. For example, your app can discover, explore, and interact with low energy peripheral devices, such as heart rate monitors, digital thermostats, weight machine, and pedometers.
The technology of Bluetooth low energy is based on the Bluetooth 4.0 specification. This framework hides the complex or low-level details of the specification from the developers, and makes it very easy to develop the app that wants to communicate with Bluetooth devices.
There are two things that perform main role in Bluetooth communication; these are the Central and the peripheral. A central is that which wants information in order to accomplish a particular task. A central perform a number of common task like discovering and connecting to available peripherals, interacting with the peripherals data. A peripheral is one, which collects and publishes data that is needed by other devices. A peripheral also do some common task like publishing and advertising of the services, and responding to read write. The workings of these are as follows: when a central find a peripheral, the central request to connect with the peripheral and start interacting with the peripheral’s data.
Once the central connects to a peripheral, next it selects the data it is interested in. The data is organized in two concepts – Services and Characteristics. A service has data that describe the behavior of the devices. For example, in the heart rate monitor, the service is exposing heart rate data from monitor’s heart rate sensor. And characteristics provide further details about a peripheral’s service. For example, for heart rate service the characteristics might be describing the intended body location of the device’s heart rate sensor. A device can have more than one service and a service can have more than one characteristics.
In this way the Core Bluetooth framework make it easy for developers to developing apps that communicate with the Low Energy Bluetooth devices.