I just created one new cordova ios project via CLI, and i opened that project in Xcode 7.1 and while running on simulator am getting some error on mainViewController.xib, if we clicked on that error its showing xib file and on top of that showing one warning message "An internal error occurred. Editing functionality may be limited" . So am unable to run this project.
I don't know whether this is due to Xcode bug or cordova bug or any other settings issue in my Xcode.
I had this issue and clearing derived data folder fixed the issue for me
Preferences > Locations > Derived Data > click the arrow to open in Finder > trash it.