XCode has a very handy little utility that allows you to preview your user interface. You can pick and choose preview for different devices. You can preview in different orientations as well as pick localized view. You are not limited to preview of one device at a time. You can add previews for multiple devices at same time. You can even add preview for same device multiple times in your view. Following screenshot shows that by clicking on + icon at bottom left of preview windows you can add more previews.
You can add multiple views by clicking on that icon. But it is not very obvious is how to get rid of multiple views that you have added. It is very simple to remove storyboard previews. Click on the view that you want to remove in preview windows and hit Delete. It will remove that preview.