Initializes a two-channel (stereo) PCM audio buffer for computed audio data (versus pre-recorded audio)

BufferSamples.m

AVAudioPCMBuffer * (^bufferSamples)(AVAudioFrameCount, AVAudioChannelCount,  AVAudioFormat *, double) = ^AVAudioPCMBuffer *(AVAudioFrameCount frame_count, AVAudioChannelCount channel_count, AVAudioFormat *audioFormat, double duration_n_secs)
{
    AVAudioFrameCount frameCount = audioFormat.sampleRate * duration;
    AVAudioPCMBuffer *pcmBuffer = [[AVAudioPCMBuffer alloc] initWithPCMFormat:audioFormat frameCapacity:frameCount];
    pcmBuffer.frameLength = frameCount;
    float *left_channel  = pcmBuffer.floatChannelData[0];
    float *right_channel = (channelCount == 2) ? pcmBuffer.floatChannelData[1] : nil;
    
    int amplitude_frequency = arc4random_uniform(8) + 4;
    for (int index = 0; index < frame_count; index++)
    {
        double time = index / frame_count;
        double frequency = sinf(2.0 * M_PI * (frequency * duration) * time) * 0.5; // Multiply the frequency by the duration to ensure the right pitch, regardless of the length of the buffer
        if (left_channel)  left_channel[index]  = frequency;
        if (right_channel) right_channel[index] = frequency;
    }
    
    return pcmBuffer;
};