How do you populate the Xcode 4 “Option+Click” popover?

Question

In Xcode 4, if you option + click on a keyword, then the said keyword will appear in a popover with a bunch of descriptive information, like so:

Answer 1

As of Xcode 5.0, Doxygen and HeaderDoc formatting for variables and methods is automatically parsed and rendered in the Quick Help popover. More information about it here, but here's some key bits:

/**
 * Add a data point to the data source.
 * (Removes the oldest data point if the data source contains kMaxDataPoints objects.)
 *
 * @param aDataPoint An instance of ABCDataPoint.
 * @return The oldest data point, if any.
 */
 - (ABCDataPoint *)addDataToDataSource:(ABCDataPoint *)aDataPoint;

renders in Xcode as:

As for properties, it's as easy as:

/// Base64-encoded data.
@property (nonatomic, strong) NSData *data;

When option-clicked, this lovely popover appears: