Building Cocoa Applications: A Step by Step Guide

The NSScrollView and NSTextView Classes

In Chapter 10 we introduced the NSScrollView and NSTextView classes when we dragged an NSScrollView object from IB’s Cocoa-Data palette into a MathPaper window. At the time, we said that the NSScrollView object “contains” an NSTextView object. Perhaps a better way of putting it is to say that an NSTextView is “embedded” inside each NSScrollView. The NSScrollView object in IB’s Palettes window actually contains the following nine objects:

NSScrollView

Displays the scroller and does the actual scrolling

NSTextView

Displays the text

NSClipView

Helps arrange the communication between the NSScrollView and the NSTextView

Vertical scroller

Controls up-down scrolling and shows where you are in the document

Horizontal scroller

Controls left-right scrolling and shows where you are in the document

NSTextStorage object

Holds the data that the NSTextView displays

NSTextContainer object

Defines the region where the text will be displayed

NSLayoutManager object

Controls the layout of the NSTextStorage object’s information within the NSTextView

NSSimpleHorizontalTypesetter

Does the typesetting

You can control whether each scroller is displayed by sending the setHasVerticalScroller: or setHasHorizontalScroller: messages (with the arguments YES or NO) to the NSScrollView. By default, the NSScrollView that you drag off IB’s Cocoa-Data palette displays the vertical scroller, but not the horizontal one.

NSTextView objects are most frequently used with NSScrollView ...