importing projects in Xcode

I have an iPhone app, that contains a lot of "sub-apps". I basically develop each component separately as it's own 开发者_运维百科project, and when I feel that it is ready, I manually drag all the files into Xcode. I know you can import Xcode projects into other projects, but I'm not really sure what this does. Does any have a better way to do this?

You can specify multiple targets in one project with different source and resources making up each one. You can also (if necessary) specify dependencies between targets, if for example you have a plugin target which must be built and copied into a main application target.

This documentation from Apple is a good place to start:

http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/XcodeBuildSystem/100-Targets/bs_targets.html