Working with Views and Storyboards
The most common part of every program’s user interface is a window that displays items such as buttons and text fields. In Xcode, windows are called views. In all but the simplest programs, a user interface will likely consist of two or more windows or views. That means your program needs to know how to open additional windows and close them again.
The two ways to create and store views are .xib files and .storyboard files. An .xib file holds one view so if you need to display multiple views, you’ll need to create multiple .xib files. A .storyboard file can hold one or more views.
You can create user interfaces with either .xib or .storyboard files, or a combination of both. Generally, .storyboard ...