MapKit and Text Input - iOS Programming: The Big Nerd Ranch Guide - page 167

MKMapView must implement a method that zooms in on a location. Let's track down this
method in the API Reference.
Search for the MKMapView class. In the class reference page, look for Manipulating the
Visible Portion of the Map in the Tasks section. There are a handful of methods and prop-
erties in this section; we'll start at the top with the region property. The details for re-
gion tell us that this property is of type MKCoordinateRegion and that it provides
an implicit zoom. Sounds perfect. But to set this property, we need to know more about
MKCoordinateRegion .
Search for MKCoordinateRegion . Its details are in the Map Kit Data Types Referen-
ce . MKCoordinateRegion has two members of types CLLocationCoordin-
ate2D and MKCoordinateSpan . The CLLocationCoordinate2D is the center of
the map and the MKCoordinateSpan determines the level of zoom ( Figure 5.12 ).
Figure 5.12 Parts of an MKCoordinateRegion
To set the region property of the map view, we'll need to package up one of these in-
stances, so let's find out how we can do this. Search again for MKCoordinateRegion
and this time select the Map Kit Functions Reference . One of these functions,