The view hierarchy is a tree of view objects that exists at run time. A typical program will have a fairly static layout of views defined in Interface Builder, but you don’t have to restrict yourself to this.
The view hierarchy is a dynamic structure and, just like the rest of a Cocoa program, can be introspected and modified while a program runs. Interface Builder allows you to create
NSView objects in a nib file that have their own view hierarchy not connected to any window. This allows views to be created at design time, but not inserted into a window until run time. You can use this to implement a variety of dynamic behaviors.
The most commonly used dynamic view is the tab view. The
NSTabView class ...