Racket gesture using the accelerometer/gyroscope on iPhone

Hello everyone,
I've been using Unity for a few months and I managed to figure out most of the problems by my own but when it comes to the accelerometer/gyroscope related stuff, I do not have any idea where to start from. I needed some help to write a function that detects if the user swings the phone like a racket (both for left and right handed people). It doesn't necessarily need to be very accurate but, for instance, it should not recognize a shake gesture as a racket gesture. Is there some one fond of accelerometers and gyroscope able to help me out?

Thank you very much in advance