I want to control the transport on iPad audio playback samples (GarageBand perhaps) using the MC8. I want to play, pause,stop, rewind, and next track. Does this require Sysex messages or something simpler?
It’ll depend on what iPad app you are using. Most with a MIDI implementation should be using just CC messages - I’m not familiar with any that requires SysEx messages to be sent.
I do this with Camelot on the iPad. You can control audio samples in their timeline function. It is possible that you can also do this with GarageBand, I have not tried that. But Camelot can be controlled to load different songs with different samples through midi commands, and then control payback also via midi. There are probably a host of other apps than can also do this, but this method works for me in a live setting.