Read the WAV file and convert it to an array of amplitudes in Swift

Question

I followed a very good guide to Udacity to learn the basics of sound applications with Swift . I would like to expand its current functionality, starting with displaying the waveform of a WAV file. To do this, I would need to extract the amplitude depending on the sample from the WAV file. How can I continue in fast, given that I already have a recorded file?

Thanks!