Should *.xccheckout files in Xcode5 be ignored under VCS?

You should check in an Xcode 5 .xccheckout file; in general, files in xcshareddata should be committed.

An .xccheckout file contains metadata about what repositories are used in a workspace. For a single project in a single repository that doesn't make much difference. But if you're using a workspace that has multiple projects from different repositories, the presence of an .xccheckout file in the workspace allows Xcode to know what all of the components that make up a workspace are and where to get them.

The *.xccheckout file contains VCS metadata, and should therefore not be checked into the VCS.

On the other hand: checking in this file will probably not create merge difficulties or other problems.

If you want to ignore this file (which I recommend) you should add this line to your project's .gitignore:

*.xccheckout

Abizern's solution will not work for projects inside a workspace. Because, when you use a workspace, the path to the *.xccheckout file will be: <workspace-name>.xcworkspace/xcshareddata/<workspace-name>.xcchekout. And it actually ignores more than you would want.

Edit:This file exists for managing Xcode's knowledge of the possibly many VCS systems in your project, see Chris Hanson answer. For > 99% of the projects the .xccheckout file is configuration overkill.

It depends. The file contains references to the remote repository you are using. If you are using a centralized VCS such as Perforce or Subversion, everyone's remote repository will be the same and so you can and should check the file in.

If you are using a distributed VCS such as Mercurial or git, but using it as though it were a CVCS (in other words, everyone cloned from a shared repository directly to their personal workspace on their machine) then you still might want to check it in.

However, if you are using a DVCS with everyone having their own remote clone, for example using GitHub in it's standard usage pattern, you DO NOT want to check this file in. If you did then your Pull Requests will be asking for your repository settings to get copied into everyone else's xccheckout file, but your repository settings will be different from everyone else's because you are all using different remote repositories.