Quote Originally Posted by DanielJazz View Post
It looks like GarageBand on iPhone has a means for doing this by using the Inter-App Audio Apps which is listed as an instrument. However I have not been able to determine how this feature is used.
Yes it is possible to use either inter-app audio or AudioBus app.
I can only check on iPad at the moment (presumably it is the same on iPhone). I can see the option of Inter-app audio within the Instrument choices, then choose iReal Pro in the Instruments tab. Set the + song section recording length to automatic; Tap the record button then switch to iReal Pro and tap Play.
With AudioBus, choose iReal Pro as the Input and GB as output. You will see its play or record buttons within the connected apps.

Both record in real-time. Currently we find AudioBus better implemented (it is a separate app).
However I find using AudioShare app an easy way to import the rendered audio track when using GB (and it is similar to how you would do it on computer, exporting from one app then importing the audio file to a DAW).