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.

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.