How to record only the last 10 seconds of audio using AVAudioRecorder?

This might be a very simple request so apologies if it is.

I'm using AVAudioRecorder to record sound from the iphone's mic. Currently I'm saving this to a file. The recording is only stopped once the user taps a button and is then played back.

My question is how would I get it so that the audio recorder only saves the last 10 seconds of sound?

I know I could probably get the player to only play fro开发者_C百科m the last 10 seconds but I don't want the recorded audio file to get huge. I'd prefer to just record the last 10 seconds.

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Don't use the AVAudioRecorder API. It can't do what you want. Use the Audio Queue API (or maybe the RemoteIO Audio Unit) to record samples to a circular buffer 10 seconds long (that's less than 1 megabyte in size). Then unroll this circular buffer when writing the samples out to a .wav file following a WAVE/RIFF file header.