Cannot Merge due to conflict with UserInterfaceState.xcuserstate

just remove files using

git rm --cached *xcuserstate

then do a local commit selecting .DS_Store with miscellaneous message

discard all other changes

pull

push

done :)

UserInterfaceState.xcuserstate is where Xcode saves your GUI states, such as window positions, open tabs, expanded nodes in the project inspector etc.

Simply resizing the Xcode window will cause this file to change and be flagged as modified by your source control system. You can make your SCM system ignore specific files that are not important to the project itself.

Git: Git ignore file for Xcode projects
Subversion: SVN ignore pattern with Xcode 4