Get in app sounds onto your computer or mac?

Find the .ipa on your computer.
Duplicate the file.
Change the duplicate to .zip.
Unzip it.
Find the sound files in the bundle.
Use them elsewhere.

The Apple AV Cable does exactly that what you want. At the audio end you will need a 2xRCA (left/right, also called cinch connector) to TRS (also called an audio jack, phone plug, jack plug, stereo plug, mini-jack, mini-stereo) converter. I am using that often. Plug it into MBP Mic IN, adjust Mic level and record with Quicktime. Works perfect. (Sorry iPhone has no digital I/O.)

http://en.wikipedia.org/wiki/TRS_connector
http://en.wikipedia.org/wiki/RCA_jack

Apple AV Cable:
http://store.apple.com/us/product/MB128LL/B
Better take the Composite version because it's video part (maybe you'll need it sometimes) is compatible with almost each TV set here on this planet:
http://store.apple.com/us/product/MB129LL/B

I wrote a review of that cable. Sorry it's German language but there are some photos anyway.

There might be legal implications in terms of sound licensing. We had to pay for all of the effects in Blipr. Probably not much of a concern if you aren't using them in commercial works but something you might want to look into, none the less.