Swift - AudioKit AKMidi to AKSequencer - ios

Question

I currently have an application which uses an AKKeyboard to create sounds using an Oscillator. Whenever the keyboard is played I get the MIDI data also. What I would like to do is create an AKSequence from the MIDI data I receive.
Any advice or pointers will be greatly appreciated, thank you.
Here is a partial amount of my code:
var bank = AKOscillatorBank()
var midi: AKMIDI!
let sequencer = AKSequencer()
let sequenceLength = AKDuration(beats: 8.0)
func configureBank() {
AudioKit.output = bank
do {
try AudioKit.start()
} catch {
AKLog("AudioKit couldn't be started")
}
midi = AudioKit.midi
midi.addListener(self)
midi.openInput()
}
// AKKeyboard Protocol methods
func noteOn(note: MIDINoteNumber) {
let event = AKMIDIEvent(noteOn: note, velocity: 80, channel: 5)
midi.sendEvent(event)
bank.play(noteNumber: note, velocity: 100)
}
func noteOff(note: MIDINoteNumber) {
let event = AKMIDIEvent(noteOff: note, velocity: 0, channel: 5)
midi.sendEvent(event)
bank.stop(noteNumber: note)
}
// AKMIDIListener Protocol methods..
func receivedMIDINoteOff(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel) {
print("ReceivedMIDINoteOff: \(noteNumber), velocity: \(velocity), channel: \(channel)")
}

Answer 1

You don't actually need to build the sequence directly from the AKMIDIEvents. Just query the sequence's currentPosition when you call AKKeyboardView's noteOn and noteOff methods and programmatically add events to a sequencer track based on this.
The process is basically identical to this (minus the final step, of course): https://stackoverflow.com/a/50071028/2717159
Edit - To get the noteOn and noteOff times, and duration:
// store notes and times in a dictionary:
var noteDict = [MIDINoteNumber: MIDITimeStamp]()
// when you get a noteOn, note the time
noteDict[currentMIDINote] = seq.currentPosition.beats
// when you get a noteOff
let endTime = seq.currentPosition.beats
if let startTime = noteDict[currentMIDINote] {
let durationInBeats = endTime - startTime
// use the startTime, duration and currentMIDINote to add event to track
noteDict[currentMIDINote] = nil
}