Previewing Your User Interface
Use the built-in preview assistant editor to see how your user interface appears on different devices and in different languages without compiling your app. You can open multiple preview editors to see different devices, orientations, and languages. Changes made in the storyboard or xib file editor are instantly reflected in the preview.
For information on how to do this, see Previewing Your Layout for Different Localizations, iOS Devices, and iOS Versions.