There are 2 repositories under audiotoolbox topic.
Streaming and realtime audio manipulation with AVAudioEngine
An extension on AVPlayer which converts it to have all useful features of AVAudioPlayer but with streaming support. Also added additional methods to support Audio visualization from AVPlayer streaming.
Simple command-line utilities designed for BetterTouchTool presets.
Core Audio, Audio Toolbox, and AVFAudio utilities
Play MIDI files from the command line on macOS. Supports CoreMIDI devices.
Device Functionality Checking using CoreBluetooth, CoreLocation, AVFoundation, CoreMotion, LocalAuthentication, AudioToolbox, Speech, UIDevice.
Stanford CS193p course (2018). The game is based on the lectures of this course, but I have made some improvements. Contains: UIKit, Foundation, AudioToolbox, Hashable