In Xcode, go to Preferences and download more simulators. It won't get you every OS, but a pretty good selection. 

On Monday, June 22, 2015, Joaquin Oltra Hernandez <jhernandez@wikimedia.org> wrote:
Hey, when debugging web stuff on the iOS simulator, I see that I can change the device going to the menu bar Hardware > Device. But I can't seem to find how to change operating system versions, I'm stuck with 8.2.

I'm sure this is super obvious for the iOSers and I would appreciate some pointers :)

Thanks!