You might remember Klimper, the developer describes it as:

Klimper is a mobile music creation studio with inspiring music theory features that helps you create and develop ideas while making complex songwriting tasks easy.

  • Support for Instrument Apps via Inter-App-Audio and Audio Unit Extensions
  • Grouping Feature to build and arrange whole song parts easily
  • New UI color scheme
  • New Getting Started Tutorial
  • Lots of internal improvements and bugfixes

The developer also says that support is on the way for Ableton Link, Audiobus 3 and MIDI Out. All of which will be very handy indeed.