No problem, you can always use the analog output of your mixer and connect directly to the microphone input of your Device. Usually microphone inputs are monaural (one channel) not stereo)

There are also some inexpensive stereo audio to USB converters on the market (although they all say they're for a PC) . The caveat here is that most require a microphone level input. You'll need to take a look at some of the options listed under the 'Audio' topic Connecting Your Instrument, Or Keyboard To Your Device

Here's the one that I've been using for Streaming the JOJS Jam sessions (into a PC Laptop).

Vantec NBA-200U USB External 7.1 Channel Audio Adapter (Windows)

Sorry I can't find one that specifically mentions iPhone or iPad.

With the right set of adapters and a breakout cable to convert the stereo audio from your mixer to an 1/8" trs 3.5mm) plug, (and the appropriate adapter for your tablet or smart phone if needed) your good to go.