iPhone - Recording audio played only by app

I'm creating some applicatio开发者_Go百科n that plays sounds like piano, drums etc. I have a recording feature in that. Its recording well and good. I'm using AVAudioRecorder. But along with application sound, outside sound is also being added. How can I make my recorder record only app sounds..... Is there any other class/framework that I've to use.

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There is no API that will redirect an iPhone app's audio output to a file.

I think your only option is to use a low level audio API (either AudioQueues or RemoteIO units) and when recording write the samples out to a file (via a buffer) as well as to the speaker.

This would require you to generate, arrange and mix the instrument samples, something wouldn't have to worry about with a higher level API.