Xcode’s documentation integration is a useful tool. Its Quick Help feature (the option-click bubble and the Utilities panel) relies on “documentation sets” to provide contextual descriptions of symbols within an API. You’re not limited to Apple’s documentation, however. You can add your own.
Prompted by a question on StackOverflow, where the poster was asking how to get his own documentation into the Quick Help bubble, I remembered reading that this was possible. You just need to provide your own documentation set for your API.
Xcode 4′s contextual help, which Apple calls “Quick Help,” relies entirely on the installed documentation sets. Xcode 4 automatically downloads the documentation sets (including updates) for the Mac OS and iOS APIs but you can install third-party sets as well. The Documentation Set Guide, included in the “Tools Guides” of the Xcode 4.0 Developer Library contains complete instructions for creating your own set. I won’t reproduce the particulars here but you can find the guide by opening Xcode’s documentation browser (in the Organizer window – Cmd-Shift-2).
Once you create your documentation set, you can install it in Xcode’s preferences (under the Documentation tab). Assuming the doc set is correctly built and installed, Quick Help should “just work.” Of course this is of limited use unless you’re sharing complex API with a group or the wide world.