Cocoa Text System Overview
The Cocoa Text System, aka “Text Kit” on iOS.
This revolves around everything related to accepting textual user input on the Mac:
NSTextView for the UI component,
NSTextStorage for the processing of text and style changes,
NSLayoutManager for the computation of line and glyph sizes, and for applying styles,
NSTypesetter for putting glyphs on the screen. Even
NSTextFields are just reusing a shared
NSTextView as the field editor. It’s everywhere.