Something important to consider is whether this beat analyst expectations or not. Your earnings could grow by 20%, but if the stock had priced in 25% growth then you'll still see your stock drop after a report.
Anybody know whether this beat expectations or not? It doesn't explicitly say it in the press release.
Edit: According to Fortune, looks like this was a modest beat: http://fortune.com/2015/10/27/apple-beats-expectations-stock...