In RaiseMan, you are already using two nib files:
MainMenu.nib is automatically loaded by
NSApplication when the application first launches.
MyDocument.nib is automatically loaded each time an instance of
MyDocument is created. In this section, you will learn how to load nib files by using
Why would you want to load a nib file? Most commonly, your application will have several windows, such as a Find panel and a Preferences panel, that are used only occasionally. By postponing loading the nib until the window is needed, your application will launch more quickly. Furthermore, if the user never needs the window, your program will use less memory.