typedef void (*AudioQueuePRopertyListenerProc) (                void *                  inUserData,                AudioQueueRef           inAQ,                AudioQueuePropertyID    inID            );

static void propertyListenerCallback (    void                    *inUserData,    AudioQueueRef           queueObject,    AudioQueuePropertyID    propertyID) {    AudioPlayer *player = (AudioPlayer *) inUserData;        // gets a reference to the playback object    [player.notificationDelegate updateUserInterfaceOnAudioQueueStateChange: player];        // your notificationDelegate class implements the UI update method}

AudioQueueAddPropertyListener (    self.queueObject,                // the object that will invoke your callback    kAudioQueueProperty_IsRunning,   // the ID of the property you want to listen for    propertyListenerCallback,        // a reference to your callback function    self);

struct AudioStreamBasicDescription {    Float64 mSampleRate;    UInt32  mFormatID;    UInt32  mFormatFlags;    UInt32  mBytesPerPacket;    UInt32  mFramesPerPacket;    UInt32  mBytesPerFrame;    UInt32  mChannelsPerFrame;    UInt32  mBitsPerChannel;    UInt32  mReserved;				//0};typedef struct AudioStreamBasicDescription  AudioStreamBasicDescription;struct  AudioStreamPacketDescription {    SInt64  mStartOffset;    UInt32  mVariableFramesInPacket;    UInt32  mDataByteSize;};typedef struct AudioStreamPacketDescription AudioStreamPacketDescription;

- (void) calculateSizesFor: (Float64) seconds {     UInt32 maxPacketSize;    UInt32 propertySize = sizeof (maxPacketSize);     AudioFileGetProperty (        audioFileID,        kAudioFilePropertyPacketSizeUpperBound,        &propertySize,        &maxPacketSize    );     static const int maxBufferSize = 0x10000;   // limit maximum size to 64K    static const int minBufferSize = 0x4000;    // limit minimum size to 16K     if (audioFormat.mFramesPerPacket) {        Float64 numPacketsForTime =            audioFormat.mSampleRate / audioFormat.mFramesPerPacket * seconds;        [self setBufferByteSize: numPacketsForTime * maxPacketSize];    } else {        // if frames per packet is zero, then the codec doesn't know the        // relationship between packets and time. Return a default buffer size        [self setBufferByteSize:            maxBufferSize > maxPacketSize ? maxBufferSize : maxPacketSize];    }     // clamp buffer size to our specified range    if (bufferByteSize > maxBufferSize && bufferByteSize > maxPacketSize) {        [self setBufferByteSize: maxBufferSize];    } else {        if (bufferByteSize < minBufferSize) {            [self setBufferByteSize: minBufferSize];        }    }     [self setNumPacketsToRead: self.bufferByteSize / maxPacketSize];}

AudioFileCreateWithURL (    audioFileURL,    kAudioFileCAFType,    &audioFormat,    kAudioFileFlags_EraseFile,    &audioFileID   // the function provides the new file object here);

UInt32 audioInputIsAvailable;UInt32 propertySize = sizeof (audioInputIsAvailable); AudioSessionGetProperty (    kAudioSessionProperty_AudioInputAvailable,    &propertySize,    &audioInputIsAvailable // A nonzero value on output means that                           // audio input is available);

NSString *soundFilePath =                [[NSBundle mainBundle] pathForResource: @"sound"                                                ofType: @"wav"]; NSURL *fileURL = [[NSURL alloc] initFileURLWithPath: soundFilePath]; AVAudioPlayer *newPlayer =                [[AVAudioPlayer alloc] initWithContentsOfURL: fileURL                                                       error: nil];[fileURL release]; self.player = newPlayer;[newPlayer release]; [self.player prepareToPlay];[self.player setDelegate: self];

- (void) audioPlayerDidFinishPlaying: (AVAudioPlayer *) player                        successfully: (BOOL) flag {    if (flag == YES) {        [self.button setTitle: @"Play" forState: UIControlStateNormal];    }}

- (IBAction) playOrPause: (id) sender {     // if already playing, then pause    if (self.player.playing) {        [self.button setTitle: @"Play" forState: UIControlStateHighlighted];        [self.button setTitle: @"Play" forState: UIControlStateNormal];        [self.player pause];     // if stopped or paused, start playing    } else {        [self.button setTitle: @"Pause" forState: UIControlStateHighlighted];        [self.button setTitle: @"Pause" forState: UIControlStateNormal];        [self.player play];    }}

static const int kNumberBuffers = 3;// Create a data structure to manage information needed by the audio queuestruct myAQStruct {    AudioFileID                     mAudioFile;    CAStreamBasicDescription        mDataFormat;    AudioQueueRef                   mQueue;    AudioQueueBufferRef             mBuffers[kNumberBuffers];    SInt64                          mCurrentPacket;    UInt32                          mNumPacketsToRead;    AudioStreamPacketDescription    *mPacketDescs;    bool                            mDone;};// Define a playback audio queue callback functionstatic void AQTestBufferCallback(    void                   *inUserData,    AudioQueueRef          inAQ,    AudioQueueBufferRef    inCompleteAQBuffer) {    myAQStruct *myInfo = (myAQStruct *)inUserData;    if (myInfo->mDone) return;    UInt32 numBytes;    UInt32 nPackets = myInfo->mNumPacketsToRead;     AudioFileReadPackets (        myInfo->mAudioFile,        false,        &numBytes,        myInfo->mPacketDescs,        myInfo->mCurrentPacket,        &nPackets,        inCompleteAQBuffer->mAudioData    );    if (nPackets > 0) {        inCompleteAQBuffer->mAudioDataByteSize = numBytes;        AudioQueueEnqueueBuffer (            inAQ,            inCompleteAQBuffer,            (myInfo->mPacketDescs ? nPackets : 0),            myInfo->mPacketDescs        );        myInfo->mCurrentPacket += nPackets;    } else {        AudioQueueStop (            myInfo->mQueue,            false        );        myInfo->mDone = true;    }}// Instantiate an audio queue objectAudioQueueNewOutput (    &myInfo.mDataFormat,    AQTestBufferCallback,    &myInfo,    CFRunLoopGetCurrent(),    kCFRunLoopCommonModes,    0,    &myInfo.mQueue);

Float32 volume = 1;AudioQueueSetParameter (    myAQstruct.audioQueueObject,    kAudioQueueParam_Volume,    volume);

typedef struct AudioQueueLevelMeterState {    Float32     mAveragePower;    Float32     mPeakPower;};  AudioQueueLevelMeterState;

#include <AudioToolbox/AudioToolbox.h>#include <CoreFoundation/CoreFoundation.h> // Define a callback to be called when the sound is finished// playing. Useful when you need to free memory after playing.static void MyCompletionCallback (    SystemSoundID  mySSID,    void * myURLRef) {        AudioServicesDisposeSystemSoundID (mySSID);        CFRelease (myURLRef);        CFRunLoopStop (CFRunLoopGetCurrent());} int main (int argc, const char * argv[]) {    // Set up the pieces needed to play a sound.    SystemSoundID    mySSID;    CFURLRef        myURLRef;    myURLRef = CFURLCreateWithFileSystemPath (        kCFAllocatorDefault,        CFSTR ("../../ComedyHorns.aif"),        kCFURLPOSIXPathStyle,        FALSE    );     // create a system sound ID to represent the sound file    OSStatus error = AudioServicesCreateSystemSoundID (myURLRef, &mySSID);     // Register the sound completion callback.    // Again, useful when you need to free memory after playing.    AudioServicesAddSystemSoundCompletion (        mySSID,        NULL,        NULL,        MyCompletionCallback,        (void *) myURLRef    );     // Play the sound file.    AudioServicesPlaySystemSound (mySSID);     // Invoke a run loop on the current thread to keep the application    // running long enough for the sound to play; the sound completion    // callback later stops this run loop.    CFRunLoopRun ();    return 0;}