Hi
I don’t use Hapax with iPad, but I have used iPad with external midi hardware quite a lot, so if I were to configure this I’d probably use AUM as it’s quite straightforward and intuitive to route midi. I’ll assume you already have an audio/midi interface for iPad and will be routing via USB and/or DIN.
Most AUv3’s should have some default CC mappings, so you can create definition files for most of these parameters, for every app, in line with whatever you want Hapax to control. It’s best to make a new definition file for every app that you want to use, so you can quickly assign the file to the Hapax sequencer lane of your choosing. If you don’t know how to create definition files, then this post on the Squarp forum should get you started: How to sequence multiple instrument tracks Hapax
I think most AUv3 app’s will also have midi learn functionality, so you could connect Hapax and send midi cc messages in ‘Live’ mode to the iPad to get a feel for mapping custom cc messages etc. if that’s what you really need - most of the time, the standard mapping that can be found within the app or in the online manual will give you everything you need.
Hope that helps