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Advanced Text Drawing

If your program displays a lot of text or needs to arrange text in complex ways, you should use the Cocoa text system. This system provides advanced text-handling capabilities on top of basic features such as text input, layout, display, editing, copying, and pasting. The system supports multiple fonts and paragraph styles, embedded images, spell checking, nonrectangular text containers, and sophisticated typesetting features, among many other features.

Text layout is one of the most expensive drawing-related operations you can do and the Cocoa text system is optimized for the best possible performance. The text system manages a sophisticated set of caches and optimizes the times at which it performs layout to reduce the impact on your program’s drawing cycle. Of course, these optimizations work only if your program reuses its text objects, but doing so is relatively simple.

The simplest way to use the Cocoa text system is to place an NSTextView object in one of your windows. A text view object creates and maintains the text layout objects it needs to draw text and responds to user events to modify the text.

If you want to have more control over the text layout and editing behavior, you can tie into the Cocoa text system at several places. The text engine at the heart of the Cocoa text system is highly customizable. You can subclass several text system classes to provide custom layout and typesetting behavior. You can also create your own text-based views to provide features beyond what the default NSTextView offers.

For information about the Cocoa text system, you should start by reading Text System Overview. That document describes the basic concepts of the text system and introduces you to many of the classes involved in text layout and management. It also provides simple tutorials to get you started and pointers to other text-related documents.

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