Even if an XIB file can be used in different ways, its most common use is defining the interface of a single-view controller.
When you create a new view controller, you can flag the choice Also create XIB file to automatically associate an XIB file to the new view controller:
When you open the XIB file with the interface editor, you'll see that the document outline already contains some elements:
The Placeholders section includes two proxy objects that you most likely won't need to update. The File's Owner section describes the ...