Map callout expansion animation like the one in Maps when the disclosure button is pressed

When selecting the disclosure button on a callout, the callout animates to the slide over and expand into larger area with more information.

Besides making this component from scratch, does anyone know how to make annotation callouts do this?

According to this: http://www.cocoacontrols.com/controls/gikanimatedcallout , Apple is using a private API. The link above has code that tries to replicate what Apple does.