You’re previewing Ry’s Cocoa Tutorial
Undo/redo functionality is a fundamental part of an OS X application. It frees the user from the fear of permanently damaging their data. If they accidentally change something they didn’t mean to, they can simply hit Edit > Undo (or the Command+Z shortcut), and they’re back to safety. This is an incredible feature of digital documents when compared to their physical counterparts, and it’s worth taking advantage of in your own applications.
Cocoa provides comprehensive undo/redo support via its
class. It’s designed to be highly reusable, so you can leverage it
regardless of whether your app deals with text documents, image data, or custom
The general idea is to record all of the changes to a model object using
NSUndoManager. These changes can then be re-applied to the model
object to restore its previous state. In this chapter, we’ll explore the
conceptual details behind this functionality, then we’ll walk through a
simple example project that demonstrates how
typically integrated into a Mac App.
Sorry, this is the end of the preview. To read the rest of this chapter, you’ll need to purchase Ry’s Cocoa Tutorial.
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