MIDIPiano

This project is based on AVAudioEngine, the engine manage all the AVAudioNode. There are 3 kind of node:

1. Source Node: Player(play the sound), Microphone(for Mic tuning).
2. Processing Node: Mixer(internal sound recording), Audio Unit Effect.
3. Destination: Speaker, Headphones.

Please visit Apple official documentation and WWDC videos for more details.