sample iphone code for delay and echo

Does anyone know where开发者_如何学编程 i can find sample code to apply processing to audio to simulate an echo or delay effect? I am currently using AVAudioPlayer to play samples and would like to layer the effects on top. All of the references I have seen so far are very generic and related to Audio Units.

The reason that it is difficult to find sample code for this is that avaudioplayer is not really meant for effects. If you are dealing with the sample buffers directly (as in audio units), then it is a much more straight forward process, see https://github.com/mazbox/ofxmarek/blob/master/mareklib/audio/effects/DigitalDelay.h

I don't have sample code for doing echos with avaudioplayer, but the approach would be to fire off a few players at decreasing volumes at some fixed time interval. That would give you a delay effect, but it wouldn't be very complex.