Xcode 5 now has built-in support for DOxygen style comments. So, you can comment your methods like this:
/*!
* Provides an NSManagedObjectContext singleton appropriate for use on the main
* thread. If the context doesn't already exist it is created and bound to the
* persistent store coordinator for the application, otherwise the existing
* singleton contextis returned.
* \param someParameter You can even add parameters
* \returns The a shared NSManagedObjectContext for the application.
*/
+ (NSManagedObjectContext *)sharedContext;
Inline help will look like this:
Quick help will look like this:
And sidebar help will look like this:

Here's a handy code snippet you can add the your Xcode Code Snippet library to make method documentation simple:
/**
<#description#>
@param <#parameter#>
@returns <#retval#>
@exception <#throws#>
*/

Now, you can just type "doxy" and poof! You have your doxygen template.