The first time the user chooses to save a new document, it presents a dialog in which the user names and saves the document in a disk file in a user-chosen location. The Cocoa document architecture provides a framework for document-based apps to do the following things:Ĭreate new documents. If it makes sense for your users to create multiple discrete sets of data, each of which they can edit in a graphical environment and store in files, then you should plan to develop a document-based app. It’s important to choose the basic app style early in the design process because development takes quite different paths depending on that choice. Other choices include single-window utility apps, such as Calculator, and library-style “shoebox” apps, such as iPhoto. The document-based style of app is one design choice among several that you should consider when you design your app.

The Document Architecture Provides Many Capabilities for Free See Storing Documents in iCloud for more information. The system synchronizes changes to the document data without user intervention. Using iCloud, documents can be shared automatically among a user’s computers and iOS devices. Figure 1-1 Document file, object, and data model So, the document object mediates between different representations of document data, as shown in Figure 1-1. It also knows how to modify that data model consistently and write the document data back out to disk. This document object knows how to read document data from a file and create an object graph in memory for the document data model. In the context of Cocoa, a document is an instance of a custom NSDocument subclass that knows how to represent internally persistent data that it can display in a window. To users, the document is their information-such as text and graphics formatted on a page. In this sense, the document is an object in memory that owns and manages the document data. Conceptually, a document is a container for a body of information that can be named and stored in a file. There are several ways to think of a document. In Cocoa, the document-based app design is enabled by a subsystem called the document architecture, which is part of of the AppKit framework. For example, a word processor provides commands to create new documents, it presents an editing environment in which the user enters text and embeds graphics into the document, it saves the document data to disk or iCloud, and it provides other document-related commands, such as printing and version management. One app typically handles multiple documents, each in its own window, and often displays more than one document at a time. In a document-based design, the app enables users to create and manage documents containing their data. Next Previous Designing a Document-Based Appĭocuments are containers for user data that can be stored in files locally and in iCloud.

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