AVFoundation iOS 12.0 Beta 1 to Beta 2 API Differences

../Frameworks/AVFAudio.framework/Headers/AVAudioEngine.h

Added #def AVAUDIOENGINE_HAVE_AUAUDIOUNIT

Added -[AVAudioEngine connectMIDI:to:format:block:]

Added -[AVAudioEngine connectMIDI:toNodes:format:block:]

Added -[AVAudioEngine disconnectMIDI:from:]

Added -[AVAudioEngine disconnectMIDI:fromNodes:]

Added -[AVAudioEngine disconnectMIDIInput:]

Added -[AVAudioEngine disconnectMIDIOutput:]

AVCompositionTrack.h

Added -[AVMutableCompositionTrack addTrackAssociationToTrack:type:]

Added -[AVMutableCompositionTrack removeTrackAssociationToTrack:type:]