error with git when checking out

I am getting the following error开发者_如何转开发 when doing a checkout:

error: The following untracked working tree files would be overwritten by checkout:
    Examples/RKTwitter/RKTwitter.xcodeproj/project.xcworkspace/contents.xcworkspacedata
    RestKit.xcodeproj/project.xcworkspace/contents.xcworkspacedata
Please move or remove them before you can switch branches.
Aborting

What should I do? Remove it? If I want to move it, don't know where to move it

Remove it. It's just Xcode 4's workspace data file that will get recreated once you reopen the project in Xcode 4 again. Warning also says that that file was created on the other end from where you're doing the pull.

So I'm suggest you to add this file to .gitignore list and do git rm on that file where it was added in the git repo.