Xcode is stuck when trying to refactor a class
3 years later using Xcode 5, this is still a bug. Only thing to do is file a radar.
Only appears to happen some of the time however, since others have gotten it to rename a class in this SO question - Rename a class in Xcode: Refactor... is grayed out (disabled). Why?
Hold alt (option), and right click the Xcode icon, Force Quit. Open Xcode and do it again. Pain but solution.
You'll need to force XCode to quit via the Activity Monitor, and relaunch it.
Open Activity Monitor:
- CMD+Space (opens Spotlight search bar)
- Type "Activity Monitor"... it'll likely show up at the top of the list before you finish typing the whole thing
- Press enter if "Activity Monitor" app is highlighted in the spotlight list, or click on the icon.
Force Quit XCode:
- Select "XCode" from the list to highlight it
- Click the big STOP icon to force quit.