You don't even need to use Xcode proper to code-sign a Mac app. Just use the codesign command-line utility. I've developed a Mac app using only the command-line

You don't even need to use Xcode proper to code-sign a Mac app. Just use the codesign command-line utility. I've developed a Mac app using only the command-line tools that come with Xcode (via a build system, of course), not Xcode itself. To submit to the Mac App Store, I use the Application Loader app that comes with Xcode. Edit: But I do use Xcode to build, run, and submit iOS apps. Never tried to do it any other way for that platform.