Inherits from | |
Conforms to | |
Framework | /System/Library/Frameworks/Foundation.framework |
Availability | Available in Mac OS X v10.0 and later. |
Companion guide | |
Declared in | NSArchiver.h |
Related sample code |
NSArchiver
, a concrete subclass of NSCoder
, provides a way to encode objects into an architecture-independent format that can be stored in a file. When you archive a graph of objects, the class information and instance variables for each object are written to the archive. NSArchiver
's companion class, NSUnarchiver, decodes the data in an archive and creates a graph of objects equivalent to the original set.
NSArchiver
stores the archive data in a mutable data object (NSMutableData
). After encoding the objects, you can have the NSArchiver
object write this mutable data object immediately to a file, or you can retrieve the mutable data object for some other use.
In Mac OS X v10.2 and later, NSArchiver
and NSUnarchiver
have been replaced by NSKeyedArchiver
and NSKeyedUnarchiver
respectively—see Archives and Serializations Programming Guide for Cocoa.
+ archivedDataWithRootObject:
+ archiveRootObject:toFile:
– encodeRootObject:
– encodeConditionalObject:
Returns a data object containing the encoded form of the object graph whose root object is given.
+ (NSData *)archivedDataWithRootObject:(id)rootObject
The root object of the object graph to archive.
A data object containing the encoded form of the object graph whose root object is rootObject.
This method invokes initForWritingWithMutableData:
and encodeRootObject:
to create a temporary archiver that encodes the object graph.
NSArchiver.h
Creates a temporary instance of NSArchiver
and archives an object graph by encoding it into a data object and writing the resulting data object to a specified file.
+ (BOOL)archiveRootObject:(id)rootObject toFile:(NSString *)path
The root object of the object graph to archive.
The location of the the file into which to write the archive.
YES
if the archive was written successfully, otherwise NO
.
This convenience method invokes archivedDataWithRootObject:
to get the encoded data, and then sends that data object the message writeToFile:atomically:
, using path for the first argument and YES
for the second.
The archived data should be retrieved from the archive by an NSUnarchiver object.
NSArchiver.h
Returns the receiver's archive data.
- (NSMutableData *)archiverData
The receiver's archive data.
The returned data object is the same one specified as the argument to initForWritingWithMutableData:
. It contains whatever data has been encoded thus far by invocations of the various encoding methods. It is safest not to invoke this method until after encodeRootObject:
has returned. In other words, although it is possible for a class to invoke this method from within its encodeWithCoder:
method, that method must not alter the data.
NSArchiver.h
Returns the name of the class used to archive instances of the class with a given true name.
- (NSString *)classNameEncodedForTrueClassName:(NSString *)trueName
The real name of an encoded class.
The name of the class used to archive instances of the class trueName.
NSArchiver.h
Encodes a substitute name for the class with a given true name.
- (void)encodeClassName:(NSString *)trueName intoClassName:(NSString *)inArchiveName
The real name of a class in the object graph being archived.
The name of the class to use in the archive in place of trueName.
Any subsequently encountered objects of class trueName are archived as instances of class inArchiveName. It is safest not to invoke this method during the archiving process (that is, within an encodeWithCoder:
method). Instead, invoke it before encodeRootObject:
.
NSArchiver.h
Conditionally archives a given object.
- (void)encodeConditionalObject:(id)object
The object to archive.
This method overrides the superclass implementation to allow object to be encoded only if it is also encoded unconditionally by another object in the object graph. Conditional encoding lets you encode one part of a graph detached from the rest. (See Archives and Serializations Programming Guide for Cocoa for more information.)
This method should be invoked only from within an encodeWithCoder:
method. If object is nil
, the NSArchiver
object encodes it unconditionally as nil
. This method raises an NSInvalidArgumentException
if no root object has been encoded.
NSArchiver.h
Archives a given object along with all the objects to which it is connected.
- (void)encodeRootObject:(id)rootObject
The root object of the object graph to archive.
If any object is encountered more than once while traversing the graph, it is encoded only once, but the multiple references to it are stored. (See Archives and Serializations Programming Guide for Cocoa for more information.)
This message must not be sent more than once to a given NSArchiver
object; an NSInvalidArgumentException
is raised if a root object has already been encoded. If you need to encode multiple object graphs, therefore, don’t attempt to reuse an NSArchiver
instance; instead, create a new one for each graph.
NSArchiver.h
Returns an archiver, initialized to encode stream and version information into a given mutable data object.
- (id)initForWritingWithMutableData:(NSMutableData *)data
The mutable data object into which to write the archive. This value must not be nil
.
An archiver object, initialized to encode stream and version information into data.
Raises an NSInvalidArgumentException
if data is nil
.
NSArchiver.h
Causes the receiver to treat subsequent requests to encode a given object as though they were requests to encode another given object.
- (void)replaceObject:(id)object withObject:(id)newObject
An object in the object graph being archived.
The object with which to replace object in the archive.
Both object and newObject must be valid objects.
NSArchiver.h
Raised by NSArchiver
if there are problems initializing or encoding.
extern NSString *NSInconsistentArchiveException;
NSInconsistentArchiveException
The name of an exception raised by NSArchiver
if there are problems initializing or encoding.
Available in Mac OS X v10.0 and later.
Declared in NSArchiver.h
.
NSArchiver.h
© 2006 Apple Computer, Inc. All Rights Reserved. (Last updated: 2006-05-23)