There are 5 different types (MKMapType), MKMapView can display.

.standard

Displays a street map that shows the position of all roads and some road names.

Swift 2

mapView.mapType = .Standard

Swift 3

mapView.mapType = .standard

Objective-C

_mapView.mapType = MKMapTypeStandard;

.satellite

Displays satellite imagery of the area.

Swift 2

mapView.mapType = .Satellite

Swift 3

mapView.mapType = .satellite

Objective-C

_mapView.mapType = MKMapTypeSatellite;

.satelliteFlyover