I don't know if anyone is doing this, but thought I would ask.
 
I have a desktop based system running SPLAT, but also have an iPad with an interface. 
 
I'm interested in bringing iPad recordings into SONAR.  Steinberg has CuBasis/Cubase,  where you can bring projects from an iPad into a PC, but I'm not aware of a similar path for SONAR.
 
I was wondering if anyone brings things recorded on an iPad into SONAR.  If you have I'd be interested in your experiences.

Been a while since I did it, and I'm using an ipad not a computer at the moment so can't quickly check, but as I remember things -

In Cubasis, go into the "Mixdown" function.

Select Wave as file format and "Create separate files for tracks" unless you want just a stereo bounce of the entire mix.

The files should then show up as available for transfer in the ipad apps window when yiu connect the ipad to itunes and can be saved out from there.

MIDI tracks work in a similar way.

It's going to depend on the app(s) and where you're able to export, but definitely check out AUM - https://itunes.apple.com/app/id1055636344
 
You can also stream MIDI/audio into Sonar with hardware from iConnectivity - http://www.iconnectivity.com
(Note: You may be able to do this with the interface you have.)
 
And here's a good forum to check out: http://forum.audiob.us
 
Edit: AudioShare might work if your needs are modest. Same developer as AUM. https://itunes.apple.com/app/id543859300
 

TLW is right on target, I have done this successfully using Cubasis on my iPad, into Sonar. I have only used audio, not MIDI, so I am not sure if that is possible, but at least you get the audio tracks into cubasis. Good luck!

Rather than exporting/importing individual files, you want to import the entire project at once...I think.
Cubasis/Cubase does this but I only have Cubasis so I don't know how well it works, but two things are needed:
 
Project Export Function in Cubasis
Cubasis Project Importer Extension in Cubase 8 or above.
 
I imagine the importing and exporting is done over WiFi...or a USB cable?  Anyway...
Cakewalk may have something like this in development but I have no way of knowing for sure.
 
If Cakewalk made such a product for iPad for Sonar, I would buy it.
 

Cubase/Cubasis project files are in their own commercial "private" formats, just like Sonar project files, Logic projects etc.
 
So I doubt Cake could implement an import filter without upsetting Sternberg a bit.
 
Another way to get audio from an iPad into a DAW is to hook the iPad to the DAW via an interface or the iPad headphones socket, play the music on the iPad and just record it in tracks in the DAW. Slow if you've a lot of tracks to work with though.
 
I've worked with Waldorf's Nave iPad app into a DAW, but done it by syncing it's MIDI clock to the DAW via Apple's CoreMIDI, sending it MIDI from iPad apps or the DAW then recording the output as if it were a hardware synth. No idea how you'd do that in Windows though.