Communication to Bluetooth devices was possible with External Accessory Framework by registering in MFI program. But this case was until iOS 5 came with which came the CoreBluetooth Framework. But what is the difference between them?

External Accessory Framework:

1.  To use this framework we need to be registered in MFI Program and should have made our bluetooth enabled device MFI compliant. To register here as such we need not pay for Apple. But there are costs involved in getting a certificate from third parties that your hardware does not interface with iOS device.

2. It is available for  all iOS based devices that run in iOS 3.0 and above.

CoreBluetooth Framework:

1. There is no entry cost, no registration needed.

2. It is used only for devices that are compatible with Bluetooth Low Energy.  (Bluetooth Low Energy is a feature of Bluetooth 4.0  which is claimed to be consuming far less power than that of classis Bluetooth devices)

3. iPhone 4S  is the only supported iOS device that is BLE enabled, so Core Bluetooth Framework based app can at this point in time be supported only in that device.

4.  It is supported only from iOS 5.0.