BLE (Bluetooth LE) for Uπ Bleu is the best in the Bluetooth library.
iOS Bluetooth LE framework
iOS app for use with Bluefruit Bluetooth LE modules and dev boards from Adafruit (v2.0)
A simple Swift framework for building reliable Bluetooth LE apps.
A Bluetooth Low Energy browser, an open-source alternative to LightBlue for OS X
Easily communicate between iOS/OSX devices using BLE
iOS & OSX Bluetooth library for RxSwift
Closures based APIs for CoreBluetooth