Apple - Xcode Hangs at Startup

Removing the ~/Library/Saved Application State/com.apple.dt.Xcode.savedState/directory might help as well.

No need to reinstall Xcode.

Based on this: https://discussions.apple.com/thread/3830815

1. I deleted all Xcode related "Unsaved Docs" docs found via the Finder search;
2. I removed the ~/Library/Developer folder;
3. Emptied the trash.

This worked for me.

I had a similar problem where xcode was hanging on opening one particular project. I wanted a very precise fix without having to remove all the settings. I deleted proj.xcodeproj/project.xcworkspace/xcuserdata/<user>.userdatad/UserInterfaceState.xcuserstate from the .xcodeproj folder and that solved the problem.

So if you are having Xcode hang while attempting to open one particular project, this is the file that you need to delete.