Text System Architecture
The following four classes make up the core architecture of Cocoa’s text handling system:
NSTextStorageis the backbone data model responsible for storing text.
NSTextViewis responsible for presentation in the view.
NSTextContaineract as controllers between the model and the view.
The relationship between these core classes is based on the same Model-View-Controller (MVC) pattern used throughout the Application Kit (and discussed in Chapter 3). Figure 5-2 shows the division of responsibilities in these four classes using the MVC pattern.
Figure 5-2 shows the relationship between the four
classes, but doesn’t show the one-to-many
relationship that may exist between instances of these classes.
NSTextStorage own and manage one or
NSLayoutManager objects. Similarly, each
NSLayoutManager owns one or more
NSTextContainer objects, while each text container
object is paired with an
NSTextView object. The
nature of these relationships is what gives Cocoa’s
text handling system much of its flexibility and power.
represents the view, or
presentation, layer of the text system; it is the class that facilitates user interaction with the text system. User interaction consists of displaying text onscreen and ...