- macOS 10.3+
The typesetter creates line fragment rectangles, positions glyphs within the line fragments, determines line breaks by word wrapping and hyphenation, and handles tab positioning.
NSATSTypesetter encapsulates the advanced typesetting capabilities of Core Text.
NSATSTypesetter provides line and character spacing accuracy and supports many languages, including bidirectional languages.
NSATSTypesetter introduced a set of interfaces in OS X version 10.3 that facilitated subclassing and made it possible to substitute a custom layout engine into the Cocoa text system. In OS X version 10.4, those interfaces moved to
NSTypesetter, which you can subclass to the same effect. See the
NSTypesetter reference documentation for relevant subclassing notes.