18 NSUserDefaults Many applications include preferences that users can set. Whether users are picking the size of the text or storing usernames, there is a standard way of enabling iOS application preferences. In this chapter, you're going to use the NSUserDefaults class to add a preference to your Whereami application. This preference will specify the map type of the MKMapView . Updating Whereami Every MKMapView has a mapType property that specifies whether it shows roads, satellite imagery, or both. You will allow the user to change this property by adding a UISegmentedControl that toggles the map type. The user's choice will be saved as a preference, and the next time the application is launched, the preferred type of map will be displayed. Open the Whereami project. Then open WhereamiViewController.xib and add a UISegmentedControl to the interface. Change its style and number of segments to what is shown in