Every time a new beta version of Xcode comes out, we all want to jump in and try out the new features. Often we have multiple installations, sometimes even older versions installed. This post explains the best way to manage your different Xcode installs.
Xcode really does not like being run multiple times. Be sure to quit Xcode and the simulator before launching a different version.
Working with Multiple Versions of Xcode by Geoff Hackworth