Class

NSDocument

An abstract class that defines the interface for macOS documents.

Overview

A document is an object that can internally represent data displayed in a window and that can read data from and write data to a file or file package. Documents create and manage one or more window controllers and are in turn managed by a document controller. Documents respond to first-responder action messages to save, revert, and print their data.

Conceptually, a document is a container for a body of information identified by a name under which it is stored in a disk file. In this sense, however, the document is not the same as the file but is an object in memory that owns and manages the document data. In the context of AppKit, a document is an instance of a custom NSDocument subclass that knows how to represent internally, in one or more formats, persistent data that is displayed in windows.

A document can read that data from a file and write it to a file. It is also the first-responder target for many menu commands related to documents, such as Save, Revert, and Print. A document manages its window’s edited status and is set up to perform undo and redo operations. When a window is closing, the document is asked before the window delegate to approve the closing.

NSDocument is one of the triad of AppKit classes that establish an architectural basis for document-based apps (the others being NSDocumentController and NSWindowController).

Subclassing NSDocument

The NSDocument class is designed to be subclassed. That is, the NSDocument class is abstract, and your app must create at least one NSDocument subclass in order to use the document architecture. To create a useful NSDocument subclass, you must override some methods, and you can optionally override others.

The NSDocument class itself knows how to handle document data as undifferentiated lumps; although it understands that these lumps are typed, it knows nothing about particular types. In their overrides of the data-based reading and writing methods, subclasses must add the knowledge of particular types and how data of the document’s native type is structured internally. Subclasses are also responsible for the creation of the window controllers that manage document windows and for the implementation of undo and redo. The NSDocument class takes care of much of the rest, including generally managing the state of the document.

See Document-Based App Programming Guide for Mac for more information about creating subclasses of NSDocument, particularly the list of primitive methods that subclasses must override and those that you can optionally override.

Document Saving Behavior

The NSDocument class implements document saving in a way that preserves, when possible, various attributes of each document, including:

  • Creation date

  • Permissions/privileges

  • Location of the document’s icon in its parent folder’s Icon View Finder window

  • Value of the document’s Show Extension setting

Care is also taken to save documents in a way that does not break any user-created aliases that may point to documents. As a result, some methods in any class of NSDocument may be invoked with parameters that do not have the same meaning as they did in early releases of macOS. It is important that overrides of writeToURL:ofType:error: and writeToURL:ofType:forSaveOperation:originalContentsURL:error: make no assumptions about the file paths passed as parameters, including:

  • The location to which the file is being written. This location might be a hidden temporary directory.

  • The name of the file being written. It is possible that this file has no obvious relation to the document name.

  • The relation of any file being passed, including the original file, to the value in fileURL.

When updating your app to link against OS X v10.5, keep in mind that it is usually more appropriate to invoke in your app code one of the NSDocument save... methods than one of the write... methods. The write... methods are there primarily for you to override. The saveToURL:ofType:forSaveOperation:error: method that is meant always to be invoked during document saving, sets the fileModificationDate property with the file’s new modification date after it has been written (for NSSaveOperation and NSSaveAsOperation only).

Likewise, it’s usually more appropriate to invoke in your app code one of the NSDocument revert... methods than one of the read... methods. The read... methods are there primarily for you to override. The revertToContentsOfURL:ofType:error: method that is meant always to be invoked during rereading of an open document, sets the fileModificationDate property with the file’s modification date after it has been read.

iCloud Support

The NSDocument class implements the file coordination support that is required for an iCloud-enabled, document-based Mac app (see How iCloud Document Storage Works in iCloud Design Guide). In addition, this class’s methods for moving and renaming documents, new in OS X v10.8, ensure that these operations are performed in a safe manner for iCloud-enabled apps.

Multicore Considerations

In macOS 10.6 and later, NSDocument supports the ability to open multiple documents concurrently. However, this support requires the cooperation of the document object. If your document subclass is able to read specific document types independently of other similar documents, you should override the canConcurrentlyReadDocumentsOfType: class method and return YES for the appropriate document types. If specific document types rely on shared state information, however, you should return NO for those types.

Topics

Initializing

init

Initializes and returns an empty NSDocument object.

initWithContentsOfURL:ofType:error:

Initializes a document located by a URL of a specified type.

initForURL:withContentsOfURL:ofType:error:

Initializes a document located by a URL of a specified type, but by reading the contents for the document from a different URL.

initWithType:error:

Initializes a document of a specified type.

Loading Document Data

dataOfType:error:

Creates and returns a data object that contains the contents of the document, formatted to a specified type.

fileWrapperOfType:error:

Creates and returns a file wrapper that contains the contents of the document, formatted to the specified type.

readFromData:ofType:error:

Sets the contents of this document by reading from data of a specified type and returns YES if successful.

entireFileLoaded

A Boolean value indicating whether the document’s file is completely loaded into memory.

Creating and Managing Window Controllers

makeWindowControllers

Subclasses may override this method to create the initial window controller(s) for the document.

windowNibName

The name of the document’s sole nib file.

windowControllerDidLoadNib:

Sent after the specified window controller loads a nib file if the receiver is the nib file’s owner.

windowControllerWillLoadNib:

Sent before the specified window controller loads a nib file if the receiver is the nib file’s owner.

windowControllers

The document’s current window controllers.

addWindowController:

Adds the specified window controller to this document’s list of attached window controllers and sets the document of the passed-in window controller.

removeWindowController:

Removes the specified window controller from the receiver’s array of window controllers.

shouldCloseWindowController:delegate:shouldCloseSelector:contextInfo:

Invokes shouldCloseSelector with the result of canCloseDocumentWithDelegate:shouldCloseSelector:contextInfo: if the the specified window controller that is closing is the last one or is marked as causing the document to close.

Managing Document Windows

showWindows

Displays all of the document’s windows, bringing them to the front and making them main or key as necessary.

setWindow:

Sets the window Interface Builder outlet of this class.

windowForSheet

The most appropriate window (of the windows associated with the document) to use as the parent window of a document-modal sheet.

displayName

The name of the document as displayed in the title bars of the document’s windows and in alert dialogs related to the document.

setDisplayName:

Sets the name of this document for presentation to the user.

defaultDraftName

Returns the default draft name for the receiving subclass of NSDocument.

Reading From and Writing to Files

readFromFileWrapper:ofType:error:

Sets the contents of this document by reading from a file wrapper of a specified type.

fileModificationDate

The last known modification date of the document’s on-disk representation.

runModalSavePanelForSaveOperation:delegate:didSaveSelector:contextInfo:

Presents a modal Save panel to the user, then tries to save the document if the user approves the panel.

shouldRunSavePanelWithAccessoryView

A Boolean value indicating whether the document’s Save panel displays a list of supported writable document types.

keepBackupFile

A Boolean value indicating whether the document keeps the backup files created before the document data is written to a file.

backupFileURL

The URL for the document’s backup file that was created during an autosave operation.

fileURL

The location of the document’s on-disk representation.

draft

A Boolean value indicating whether the document is a draft that the user has not expressed an interest in keeping around.

Reading From and Writing to URLs

readFromURL:ofType:error:

Sets the contents of this document by reading from a file or file package, of a specified type, located by a URL.

writeToURL:ofType:error:

Writes the contents of the document to a file or file package located by a URL, formatted to a specified type.

writeSafelyToURL:ofType:forSaveOperation:error:

Writes the contents of the document to a file or file package located by a URL.

writeToURL:ofType:forSaveOperation:originalContentsURL:error:

Writes the contents of the document to a file or file package located by a URL.

fileAttributesToWriteToURL:ofType:forSaveOperation:originalContentsURL:error:

As a file is being saved, returns the attributes that should be written to a file or file package located by a URL, formatted to a specified type, for a particular kind of save operation.

saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:

Saves the contents of the document to a file or file package located by a URL, formatted to a specified type, for a particular kind of save operation.

canAsynchronouslyWriteToURL:ofType:forSaveOperation:

Returns whether the receiver can concurrently write to a file or file package located by a URL, formatted for a specific type, for a specific kind of save operation.

changeCountTokenForSaveOperation:

Returns an object that encapsulates the current record of document changes at the beginning of a save operation.

saveToURL:ofType:forSaveOperation:completionHandler:

Saves the contents of the document to a file or file package located by a URL, formatted to a specified type, for a particular kind of save operation, and invokes the passed-in completion handler.

updateChangeCountWithToken:forSaveOperation:

Records the fact that saving has succeeded and updates related aspects of the change count mechanism.

unblockUserInteraction

Unblocks the main thread during asynchronous saving.

Serialization

continueActivityUsingBlock:

Invokes the passed-in block to avoid a deadlock if performActivityWithSynchronousWaiting:usingBlock: is being invoked recursively.

continueAsynchronousWorkOnMainThreadUsingBlock:

Invokes the passed-in block on the main thread.

performActivityWithSynchronousWaiting:usingBlock:

Waits for any work scheduled by previous invocations of this method to complete, then invokes the passed-in block.

performAsynchronousFileAccessUsingBlock:

Waits for any scheduled file access to complete but without blocking the main thread, then invokes the passed-in block.

performSynchronousFileAccessUsingBlock:

Waits for any scheduled file access to complete, then invokes the passed-in block.

Autosaving

checkAutosavingSafetyAndReturnError:

Returns a Boolean value indicating whether it is probably safe to autosave document changes.

scheduleAutosaving

Schedules periodic autosaving for the purpose of crash protection.

hasUnautosavedChanges

A Boolean value indicating whether the document has changes that have not been autosaved.

autosaveDocumentWithDelegate:didAutosaveSelector:contextInfo:

Autosaves the document’s contents at an appropriate location.

autosaveWithImplicitCancellability:completionHandler:

Autosaves the document’s contents at an appropriate location if it needs autosaving.

autosavesInPlace

Returns whether the receiver supports autosaving in place.

autosavesDrafts

Returns whether the receiving subclass of NSDocument supports autosaving of drafts.

preservesVersions

Returns whether the receiving subclass of NSDocument supports Versions.

browseDocumentVersions:

Opens the Versions browser in the document’s main window.

autosavingFileType

Returns the document type that should be used for an autosave operation.

autosavingIsImplicitlyCancellable

A Boolean value indicating whether autosaving is happening now but could be safely cancelled.

autosavedContentsFileURL

The location of the most recently autosaved document contents.

iCloud Document Storage

moveDocumentToUbiquityContainer:

Moves the document into the user’s iCloud storage in response to the user choosing the Move to iCloud… menu item.

usesUbiquitousStorage

Returns whether your NSDocument subclass allows the use of iCloud document storage.

Handling Window Restoration

encodeRestorableStateWithCoder:

Saves the interface-related state of the document.

restoreStateWithCoder:

Restores the interface-related state of the document.

restorableStateKeyPaths

Returns an array of key paths representing the restorable attributes of the document.

invalidateRestorableState

Marks the document’s interface-related state as dirty.

restoreDocumentWindowWithIdentifier:state:completionHandler:

Restores a window that was associated with a document, after that document is reopened.

Supporting User Activities

userActivity

An object encapsulating a user activity supported by this document.

restoreUserActivityState:

Restores the state needed to continue the given user activity.

updateUserActivityState:

Updates the state of the given user activity.

Managing Document Status

documentEdited

A Boolean value indicating whether the document has changes that have not been saved.

fileNameExtensionWasHiddenInLastRunSavePanel

A Boolean value indicating whether the user chose to hide the name extension of the file that was selected in the Save panel for the document.

inViewingMode

A Boolean value indicating whether the document is in read-only mode.

Handling User Actions

printDocument:

Prints the receiver in response to the user choosing the Print menu command.

runPageLayout:

The action method invoked in the receiver as first responder when the user chooses the Page Setup menu command.

revertDocumentToSaved:

The action of the File menu item Revert in a document-based app.

saveDocument:

The action method invoked in the receiver as first responder when the user chooses the Save menu command.

saveDocumentAs:

The action method invoked in the receiver as first responder when the user chooses the Save As menu command.

saveDocumentTo:

The action method invoked in the receiver as first responder when the user chooses the Save To menu command.

Closing Documents

canCloseDocumentWithDelegate:shouldCloseSelector:contextInfo:

If the receiver is not dirty, this method immediately calls the shouldCloseSelector callback on the specified delegate with YES.

close

Closes all windows owned by the receiver and removes the receiver from the list of documents maintained by the document controller, which consequently releases it.

Reverting Documents

revertToContentsOfURL:ofType:error:

Discards all unsaved document modifications and replaces the document’s contents by reading a file or file package located by a URL of a specified type.

Duplicating Documents

duplicateAndReturnError:

Creates a new document whose contents are the same as the receiver and returns an error object if unsuccessful.

duplicateDocument:

Creates a copy of the receiving document in response to the user choosing Duplicate from the File menu.

duplicateDocumentWithDelegate:didDuplicateSelector:contextInfo:

Create a new document whose contents are the same as the receiver’s and notify the delegate.

Renaming Documents

renameDocument:

Renames the current document in response to the user choosing the Rename menu item.

Moving Documents

moveDocument:

Moves the document to a new location in response to the user choosing the Move To… menu item.

moveDocumentWithCompletionHandler:

Moves the document to a user-selected location.

moveToURL:completionHandler:

Moves the document’s file to the given URL.

Locking Documents

lockDocument:

Locks the document in response to the user choosing the Lock menu item.

unlockDocument:

Unlocks the document in response to the user choosing the Unlock menu item.

lockDocumentWithCompletionHandler:

Prevents the user from making further changes to the document.

lockWithCompletionHandler:

Prevents further modifications from being made to the file.

unlockDocumentWithCompletionHandler:

Allows the user to make modifications to the document.

unlockWithCompletionHandler:

Allows the user to make modifications to the file.

locked

A Boolean value indicating whether or not the file can be written to.

Printing Documents

printInfo

The printing information associated with the document.

preparePageLayout:

Invoked by runModalPageLayoutWithPrintInfo: and runModalPageLayoutWithPrintInfo:delegate:didRunSelector:contextInfo: to do any customization of the Page Layout panel pageLayout, such as adding an accessory view.

runModalPageLayoutWithPrintInfo:delegate:didRunSelector:contextInfo:

Runs the modal page layout panel with the receiver’s printing information object

runModalPrintOperation:delegate:didRunSelector:contextInfo:

Runs the specified print operation modally.

shouldChangePrintInfo:

Returns a Boolean value indicating whether the receiver should allow changes to the default NSPrintInfo object used in printing the document.

printOperationWithSettings:error:

Creates a print operation and returns it if successful.

PDFPrintOperation

A print operation that you can use to create a PDF representation of the document’s current contents.

saveDocumentToPDF:

Exports a PDF representation of the document’s current contents.

Handling Errors

presentError:modalForWindow:delegate:didPresentSelector:contextInfo:

Presents an error alert to the user as a modal panel.

presentError:

Presents an error alert to the user as a modal panel.

willPresentError:

Called when the receiver is about to present an error.

willNotPresentError:

Confirms that the given NSError object is not to be presented to the user and the error cannot be recovered from, so that cleanup can be done.

Working with Undo Manager

hasUndoManager

A Boolean value indicating whether the document owns or should own an undo manager object.

undoManager

The document’s undo manager object.

updateChangeCount:

Updates the receiver’s change count according to the given change type.

Managing File Types

fileType

The name of the document type, as specified in the app’s Info.plist file.

fileTypeFromLastRunSavePanel

The file type that was last selected in the Save panel.

isNativeType:

Returns a Boolean value indicating whether document data of the specified type is a native type—one the receiver can both read and write.

readableTypes

Returns the types of data the receiver can read natively and any types filterable to that native type.

canConcurrentlyReadDocumentsOfType:

Returns a Boolean value indicating whether the receiver reads multiple documents of the given type concurrently.

writableTypes

Returns the types of data the receiver can write natively and any types filterable to that native type.

writableTypesForSaveOperation:

Returns the names of the types to which this document can be saved for a specified kind of save operation.

fileNameExtensionForType:saveOperation:

Returns a filename extension that can be appended to a base filename, for a specified file type and kind of save operation.

Validating User Interface Items

validateUserInterfaceItem:

Validates the specified user interface item that the receiver manages.

Scripting

handleCloseScriptCommand:

Handles the Close AppleScript command by attempting to close the document.

handlePrintScriptCommand:

Handles the Print AppleScript command by attempting to print the document.

handleSaveScriptCommand:

Handles the Save AppleScript command by attempting to save the document.

objectSpecifier

Returns an object specifier for the document.

lastComponentOfFileName

Sets the document name to the given string in terms of the scripting name property (the name a script writer would use to specify the document in a script).

Deprecated Methods

canCloseDocument

This method is no longer supported.

dataRepresentationOfType:

A primitive method overridden by subclasses to return a data object that represents the data of the receiver in a given type.

Deprecated
fileAttributesToWriteToFile:ofType:saveOperation:

Returns the file attributes that should be written to the named document file of the specified type.

Deprecated
fileName

Returns the filename (as a fully qualified path) under which the receiver has been saved.

Deprecated
fileNameFromRunningSavePanelForSaveOperation:

Returns the filename entered into the Save panel.

fileWrapperRepresentationOfType:

Returns an NSFileWrapper object that represents the data of the receiver in a given type.

Deprecated
initWithContentsOfFile:ofType:

Initializes and returns an NSDocument object.

Deprecated
initWithContentsOfURL:ofType:

Initializes and returns an NSDocument object of a given document type.

Deprecated
loadDataRepresentation:ofType:

Overridden by subclasses to load document data.

Deprecated
loadFileWrapperRepresentation:ofType:

Loads document data from a given file wrapper.

Deprecated
printShowingPrintPanel:

Overridden by subclasses to print the current document’s (the receiver’s) data.

Deprecated
readFromFile:ofType:

Reads and loads document data of the given type from the given file.

Deprecated
readFromURL:ofType:

Reads and loads document data.

Deprecated
revertToSavedFromFile:ofType:

Reverts the receiver to the data stored in the file system.

Deprecated
revertToSavedFromURL:ofType:

Reverts the receiver.

Deprecated
runModalPageLayoutWithPrintInfo:

Runs the page layout modal panel with the receiver’s printing information object.

Deprecated
saveToFile:saveOperation:delegate:didSaveSelector:contextInfo:

Called after the user has been given the opportunity to select a destination through the modal Save panel.

Deprecated
saveToURL:ofType:forSaveOperation:error:

Saves the contents of the document to a file or file package located by a URL, formatted to a specified type, for a particular kind of save operation, and returns YES if successful.

Deprecated
setFileName:

Sets the file (filename and directory path) under which document data is saved.

Deprecated
shouldCloseWindowController:

Gives the user an opportunity to save the document.

validateMenuItem:

Validates the Revert menu item and items selected from the Save panel’s pop-up list of writable document types items.

writeToFile:ofType:

Writes document data to a file.

Deprecated
writeToFile:ofType:originalFile:saveOperation:

Writes the receiver document’s contents to a file.

Deprecated
writeToURL:ofType:

Writes document data to a URL.

Deprecated
writeWithBackupToFile:ofType:saveOperation:

This method is called by action methods to save document contents to a file.

Deprecated

Constants

NSSaveOperationType

A save operation type specifies the type of document save operation to perform. These values are used with method parameters of type NSSaveOperationType. Depending on the method, the save operation type can affect the title of the Save dialog and can affect which files are displayed in the dialog.

NSDocumentChangeType

Values that indicate a document’s edit status.

Document URL User Activity Key

When NSUbiquitousDocumentUserActivityType is present in a CFBundleDocumentTypes entry, AppKit automatically creates an NSUserActivity object for documents in iCloud, using the given activity type. The associated document’s URL is placed in the NSUserActivity object’s userInfo dictionary under this key.

Relationships

Inherits From

See Also

Documents

NSDocumentController

An object that manages an app's documents.

NSPersistentDocument

A document object that can integrate with Core Data.