Have you looked into the Traktor Audio 2 soundcard? I confess that I have up til now only used it with Traktor dj ios app (which it connects natively) but the threads here suggest that it works with other ios apps
http://community.algoriddim.com/algoriddim/topics/djay-2-7-with-traktor-audio-2-on-ios-8-x-fix
https://www.native-instruments.com/forum/threads/using-audio-2-mkii-with-ios-apps-other-than-traktor-dj-how.217886/
its a useful thing to have anyway (smaller than a deck of cards), connects straight to ipad (no camera connnection necessary) and you can buy the optional power source separately to keep the ipad charged
