As AudioKit AKOperations can't trigger arbitrary code, I made 2 classes to solve the problem using AKSequencer.
SelectorMidiInstrument.swift is a dummy AKMidiInstrument that trig functions each time it recaive a NoteOn
SelectorClock.swift instanciates a SelectorMidiInstrument slaved by a sequencer.
So you can very easily hook any function to be triggered at regular intervals.
I posted an example of ViewController that uses SelectorClock.
I tried to document my code so it should be very easy to tweak to fit your needs.
:-)