AudioToolbox.m

- (void)playBeepAudio {
    // Step 1: Dispose & Stop the last queue
    if (_queue) {
        [self stopAudio];
        [self disposeAudioQueue];
        _queue = nil;
    }

    // Step 2: Prepare the description of audio buffer
    AudioStreamBasicDescription dataformat;
    dataformat.mChannelsPerFrame = ...; // mono/ stereo
    dataformat.mSampleRate = ...; // sample rate
    dataformat.mFormatID = kAudioFormatLinearPCM;
    dataformat.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;
    dataformat.mBytesPerPacket = 2 * dataformat.mChannelsPerFrame;
    dataformat.mFramesPerPacket = 1;
    dataformat.mBytesPerFrame = dataformat.mBytesPerPacket;
    dataformat.mBitsPerChannel = 16;
    dataformat.mReserved = 0;

    OSStatus status;
    uint8 *audio = ...; // audio buffer
    UInt32 bufferSize = ...; // audio buffer size

    // Step 3: Set up the complete callback
    status = AudioQueueNewOutput(
                     &dataformat,
                     BufferCallback,
                     (__bridge void * _Nullable)(self),
                     CFRunLoopGetCurrent(),
                     kCFRunLoopCommonModes,
                     0,
                     &_queue
                     );
    if (status != noErr) NSLog(@"AudioQueueNewOutput bitrate failed %d", status);

    // Step 4: Allocate the buffer
    AudioQueueBufferRef buffer = NULL;
    status = AudioQueueAllocateBuffer(
                              _queue,
                              bufferSize,
                              &buffer
                              );
    if (status != noErr) NSLog(@"AudioQueueAllocateBuffer failed %d", status);

    // Step 4.1: Set up the buffer data
    memset(buffer->mAudioData, 0, bufferSize);
    memcpy(buffer->mAudioData, audio, bufferSize);
    buffer->mAudioDataByteSize = bufferSize;

    // Step 5: Fill the queue buffer
    status = AudioQueueEnqueueBuffer(
                         _queue,
                         buffer,
                         0,
                         nil
                         );
    if (status != noErr) NSLog(@"AudioQueueEnqueueBuffer failed %d", status);

    // Step 6: Start to play
    status = AudioQueueStart(_queue, nil);
    if (status != noErr) NSLog(@"AudioQueueStart failed %d", status);
}