Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
A mystery to me: why no midi out?
I'm new to iOS apps, but one thing has nagged me from the get go: Most iOS synths receive, but do not seem to transmit midi other than clock. I've got Thor, Mitosynth, Mersenne, ReSlice, DRC and a few others that do not seem to transmit midi note data. I especially wish ReSlice had this, so I could play the arp through other synths. Of the sound creation apps I have, only Fugue Machine and FunkBox show up as a midi source in Audiobus 3. Also strange, Concentric obviously transmits midi note data, but when I look to find it as a midi source on Audiobus 3, it isn't there.
Let me know if I'm missing something very obvious - it wouldn't be the first time.