Programming iOS 9

Chapter 21. Maps

Your app can imitate the Maps app, displaying a map interface and placing annotations and overlays on the map. The relevant classes are provided by the Map Kit framework. You’ll need to import MapKit. The classes used to describe locations in terms of latitude and longitude, whose names start with “CL,” come from the Core Location framework, but you won’t need to import it explicitly.

Displaying a Map

A map is displayed through a UIView subclass, an MKMapView.

Tip

You can instantiate an MKMapView from a nib. However, you will then need to link your target manually to the MapKit framework: edit the target and add MapKit.framework under Linked Frameworks and Libraries in the General tab.

A map has a type, which is one of the following (MKMapType):

• .Standard
• .Satellite
• .Hybrid

The area displayed on the map is its region, an MKCoordinateRegion. This is a struct comprising a location (its center, a CLLocationCoordinate2D), describing the latitude and longitude of the point at the center of the region, along with a span (an MKCoordinateSpan), describing the quantity of latitude and longitude embraced by the region and hence the scale of the map. Convenience functions help you construct an MKCoordinateRegion.

In this example, I’ll initialize the display of an MKMapView (self.map) to show a place where I like to go dirt biking (Figure 21-1):

let loc = CLLocationCoordinate2DMake(34.927752,-120.217608) let span = MKCoordinateSpanMake(0.015, 0.015) let reg = MKCoordinateRegionMake(loc, ...