how does AudioUnitRender Callback get called in iphone

Question

I am a new bee to iPhone development I need to implement audio output level metering using audiouint.(without using avaudioplayer because i am using cocos sound engines, I want to change the pitch of playing sound). I got some code from the Internet but don't know how that function get called or how to call it manually. I got code from here

anybody know how to call this function manually

    static OSStatus AudioUnitRenderCallback (void *inRefCon,AudioUnitRenderActionFlags *ioActionFlags,
                                                     const AudioTimeStamp *inTimeStamp,
                                                     UInt32 inBusNumber,
                                                     UInt32 inNumberFrames,
                                                     AudioBufferList *ioData)

Thank you

Answer 1

You don't manually call the render callback. Audio on iOS (and Mac OSX, for that matter), pulls it from the callback when the system is ready to read a block.

I know this isn't a good answer for you, but I suspect that you are perhaps thinking about this problem the wrong way...