How to create an Xcode project that is not an app but is visible in other projects?

I want to create a project with a handful of categories that add useful functionality to UIKit. I want to keep this as a separate project so that it can be source-controlled separately (and eventually hosted on github, and downloadable as a dependency via cocoa pods...but let's skip this for now.)

But all the Xcode 6.1 project templates imply an app inside. When I select an empty project it complains about missing base SDK. But this cannot be set without a target present. It is quite confusing. I don't need a target. Do I? The project should be just a shell for a number of categories + a accompanying summary header file.

I want to be able to drag this project as a subproject to any other proper app project, import the summary header file and expose those categories to the main project.

Any advice?