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Oops! sorry for not making it clearer Kalimba.. Let me explain, and add that, Apples and Oranges are still both Fruits aren't they?

As are MIDI and AAC both forms of audio? Wouldn't you agree? Also note that saying "playing sound via MIDI file" is semantically not correct.. MIDI is just a sequence of bytes with a standardized representation of an instrument, note on/off op codes, as well as things like sustain, attack speed etc. This is interpreted by the sound card driver on your computer typically. iPhone does not give you access to the sound card driver in this way.. at least that I've found, if you've found something please tell me Kalimba.. But I understand your confusion I think.. I will elaborate further!! Before I do though.. Please understand the goal, people want to play sounds on the iPhone Kalimba, some people don't even know what "extension" to use.. AAC, MIDI, who cares, it's all relative.. I would bet money those sound board apps are not feeding the Sound card processor a stream of midi bytes. Because that's what I wanted to do, and spent 3 hours trying to find in apple forums and tech docs.. no go.. Save yourself some time.. Instead, why not use the MIDI sequencer/processor on your computers sound card! it's much more badass than an iPhone's anyways, and probably supports better MIDI synth..
If you need to Play individual notes, or any sound for that matter(Which is what the original posting was about), You can
1) Take an existing MIDI file that you have,fire up your fancy MIDI suite software. Or plug in the Exact note(s) you need to use (a lot of those music sound board apps you see are typically of the variety C/G major chord variations, so they always sound good

, just ask Disney lol).
2) Once you have your sample, be it a whole song in midi or just a single note, save your midi file.. Now fire up the app as fore mentioned that will convert the MIDI to the ready to use AAC format.. Convert it over!
3) THEN, refer to the Technical Q&A on the apple forum in my previous post.
4) You will get sound working on your iPhone app
Again, I apologize for posting in two locations, people are struggling with this Kalimba, and I was simply trying to help, as this works for me. Keep your criticism positive and remember the original post(s) "how the hell do I play sound".. Well, here's one way!

Or if you have something better, why not share instead of spending your time summing my post into a derogatory analogy lol!