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Authors
- Andrew Kachites McCallum (
mccallum@gnu.ai.mit.edu
)
-
- Adam Fedor (
fedor@boulder.colorado.edu
)
-
Version: 1.117
Date: 2005/11/28 15:41:33
Copyright: (C) 1995, 1996, 1997 Free Software Foundation, Inc.
- Declared in:
- Foundation/NSDictionary.h
- Conforms to:
- NSCoding
- NSCopying
- NSMutableCopying
Availability: OpenStep
This class and its subclasses store key-value pairs, where the key and the value are objects. A great many utility methods for working with dictionaries are provided as part of this class, including the ability to retrieve multiple entries simultaneously, obtain sorted contents, and read/write from/to a serialized representation.
Both keys and values are retained by the implementation, and released when either their entry is dropped or the entire dictionary is deallocated. This differs from the implementation on OS X, where keys are copied instead of being retained and must therefore implement the <NSCopying>
protocol.
Objects of this class are immutable. For a mutable version, use the NSMutableDictionary
subclass.
The basic functionality in NSDictionary
is similar to that in Java's HashMap
, and like that class it includes no locking code and is not thread-safe. If the contents will be modified and accessed from multiple threads you should enclose critical operations within locks (see NSLock
).
Method summary
+ (id)
dictionary;
Availability: OpenStep
Returns a new autoreleased empty dictionary.
+ (id)
dictionaryWithContentsOfFile: (
NSString*)path;
Availability: OpenStep
Returns a dictionary using the file located at path. The file must be a property list containing a dictionary as its root object.
+ (id)
dictionaryWithContentsOfURL: (
NSURL*)aURL;
Availability: MacOS-X 10.0.0
Returns a dictionary using the contents of aURL. The URL must be a property list containing a dictionary as its root object.
+ (id)
dictionaryWithDictionary: (
NSDictionary*)otherDictionary;
Availability: OpenStep
Returns a newly created dictionary with the keys and objects of otherDictionary. (The keys and objects are not copied.)
+ (id)
dictionaryWithObject: (id)object
forKey: (id)key;
Availability: OpenStep
Returns a dictionary containing only one object which is associated with a key.
+ (id)
dictionaryWithObjects: (
NSArray*)objects
forKeys: (
NSArray*)keys;
Availability: OpenStep
Returns a dictionary created using the given objects and keys. The two arrays must have the same length. The n th element of the objects array is associated with the n th element of the keys array.
+ (id)
dictionaryWithObjects: (id*)objects
forKeys: (id*)keys
count: (unsigned)count;
Availability: OpenStep
Returns a dictionary created using the given objects and keys. The two arrays must have the same size. The n th element of the objects array is associated with the n th element of the keys array.
+ (id)
dictionaryWithObjectsAndKeys: (id)firstObject
,...;
Availability: OpenStep
Returns a dictionary created using the list given as argument. The list is alternately composed of objects and keys. Thus, the list's length must be pair.
- (
NSArray*)
allKeys;
Availability: OpenStep
Returns an array containing all the dictionary's keys.
- (
NSArray*)
allKeysForObject: (id)anObject;
Availability: OpenStep
Returns an array containing all the dictionary's keys that are associated with anObject.
- (
NSArray*)
allValues;
Availability: OpenStep
Returns an array containing all the dictionary's objects.
- (unsigned)
count;
Availability: OpenStep
Returns an unsigned integer which is the number of elements stored in the dictionary.
- (
NSString*)
description;
Availability: OpenStep
- (
NSString*)
descriptionInStringsFileFormat;
Availability: OpenStep
- (
NSString*)
descriptionWithLocale: (
NSDictionary*)locale
indent: (unsigned int)level;
Availability: OpenStep
Returns the receiver as a text property list in the traditional format.
See
[NSString -propertyList]
for details.
If
locale is
nil
, no formatting is done, otherwise entries are formatted according to the
locale, and indented according to
level.
Unless
locale is
nil
, a
level of zero indents items by four spaces, while a
level of one indents them by a tab.
If the keys in the dictionary respond to
[NSObject -compare:]
, the items are listed by key in ascending order. If not, the order in which the items are listed is undefined.
- (id)
init;
Availability: OpenStep
In MacOS-X class clusters do not have designated initialisers, and there is a general rule that -init
is treated as the designated initialiser of the class cluster, but that other intitialisers may not work s expected an would need to be individually overridden in any subclass.
GNUstep tries to make it easier to subclass a class cluster, by making class clusters follow the same convention as normal classes, so the designated initialiser is the richest initialiser. This means that all other initialisers call the documented designated initialiser (which calls -init
only for MacOS-X compatibility), and anyone writing a subclass only needs to override that one initialiser in order to have all the other ones work.
For MacOS-X compatibility, you may also need to override various other initialisers. Exactly which ones, you will need to determine by trial on a MacOS-X system... and may vary between releases of MacOS-X. So to be safe, on MacOS-X you probably need to re-implement all the class cluster initialisers you might use in conjunction with your subclass.
- (id)
initWithContentsOfFile: (
NSString*)path;
Availability: OpenStep
Initialises the dictionary with the contents of the specified file, which must contain a dictionary in property-list format.
In GNUstep, the property-list format may be either the OpenStep format (ASCII data), or the MacOS-X format (UTF-8 XML data)... this method will recognise which it is.
If there is a failure to load the file for any reason, the receiver will be released and the method will return nil
.
Works by invoking [NSString -initWithContentsOfFile:]
and [NSString -propertyList]
then checking that the result is a dictionary.
- (id)
initWithContentsOfURL: (
NSURL*)aURL;
Availability: MacOS-X 10.0.0
Initialises the dictionary with the contents of the specified URL, which must contain a dictionary in property-list format.
In GNUstep, the property-list format may be either the OpenStep format (ASCII data), or the MacOS-X format (UTF-8 XML data)... this method will recognise which it is.
If there is a failure to load the URL for any reason, the receiver will be released and the method will return nil
.
Works by invoking [NSString -initWithContentsOfURL:]
and [NSString -propertyList]
then checking that the result is a dictionary.
- (id)
initWithDictionary: (
NSDictionary*)otherDictionary;
Availability: OpenStep
Initializes with the keys and objects of otherDictionary. (The keys and objects are not copied.)
- (id)
initWithDictionary: (
NSDictionary*)other
copyItems: (BOOL)shouldCopy;
Availability: OpenStep
Initialise dictionary with the keys and values of otherDictionary. If the shouldCopy flag is YES
then the values are copied into the newly initialised dictionary, otherwise they are simply retained.
- (id)
initWithObjects: (
NSArray*)objects
forKeys: (
NSArray*)keys;
Availability: OpenStep
Initialises a dictionary created using the given objects and keys. The two arrays must have the same size. The n th element of the objects array is associated with the n th element of the keys array.
- (id)
initWithObjects: (id*)objects
forKeys: (id*)keys
count: (unsigned)count;
Availability: OpenStep
This is a designated initialiser for the class.
Subclasses
should override this method.
Initializes contents to the given
objects and
keys. The two arrays must have the same size. The n th element of the
objects array is associated with the n th element of the
keys array.
Calls
-init
(which does nothing but maintain MacOS-X compatibility), and needs to be re-implemented in subclasses in order to have all other initialisers work.
- (id)
initWithObjectsAndKeys: (id)firstObject
,...;
Availability: OpenStep
Initialises a dictionary created using the list given as argument. The list is alternately composed of objects and keys. Thus, the list's length must be pair.
- (BOOL)
isEqualToDictionary: (
NSDictionary*)other;
Availability: OpenStep
Two dictionaries are equal if they each hold the same number of entries, each key in one isEqual
to a key in the other, and, for a given key, the corresponding value objects also satisfy isEqual
.
- (
NSEnumerator*)
keyEnumerator;
Availability: OpenStep
Return an enumerator object containing all the keys of the dictionary.
- (
NSArray*)
keysSortedByValueUsingSelector: (SEL)comp;
Availability: OpenStep
Returns ordered array of the keys sorted according to the values they correspond to. To sort the values, a message with selector comp is send to each value with another value as argument, as in [a comp: b]
. The comp method should return NSOrderedSame
, NSOrderedAscending
, or NSOrderedDescending
as appropriate.
- (
NSEnumerator*)
objectEnumerator;
Availability: OpenStep
Return an enumerator object containing all the objects of the dictionary.
- (id)
objectForKey: (id)aKey;
Availability: OpenStep
Returns the object in the dictionary corresponding to aKey, or nil
if the key is not present.
- (
NSArray*)
objectsForKeys: (
NSArray*)keys
notFoundMarker: (id)marker;
Availability: OpenStep
Multiple version of
-objectForKey:
. Objects for each key in
keys are looked up and placed into return array in same order. For each key that has no corresponding value in this dictionary,
marker is put into the array in its place.
- (id)
valueForKey: (
NSString*)key;
Availability: MacOS-X 10.0.0
Default implementation for this class is to return the value stored in the dictionary under the specified key, or nil
if there is no value.
- (BOOL)
writeToFile: (
NSString*)path
atomically: (BOOL)useAuxiliaryFile;
Availability: OpenStep
Writes the contents of the dictionary to the file specified by path. The file contents will be in property-list format... under GNUstep this is either OpenStep style (ASCII characters using \U hexadecimal escape sequences for unicode), or MacOS-X style (XML in the UTF8 character set).
If the useAuxiliaryFile flag is YES
, the file write operation is atomic... the data is written to a temporary file, which is then renamed to the actual file name.
If the conversion of data into the correct property-list format fails or the write operation fails, the method returns NO
, otherwise it returns YES
.
NB. The fact that the file is in property-list format does not necessarily mean that it can be used to reconstruct the dictionary using the -initWithContentsOfFile:
method. If the original dictionary contains non-property-list objects, the descriptions of those objects will have been written, and reading in the file as a property-list will result in a new dictionary containing the string descriptions.
- (BOOL)
writeToURL: (
NSURL*)url
atomically: (BOOL)useAuxiliaryFile;
Availability: MacOS-X 10.0.0
Writes the contents of the dictionary to the specified url. This functions just like -writeToFile:atomically:
except that the output may be written to any URL, not just a local file.
- Declared in:
- Foundation/NSDictionary.h
Availability: OpenStep
Method summary
+ (id)
dictionaryWithCapacity: (unsigned)numItems;
Availability: OpenStep
Returns an empty dictionary with memory preallocated for given number of entries. Although memory space will be grown as needed when entries are added, this can avoid the reallocate-and-copy process if the size of the ultimate contents is known in advance.
- (void)
addEntriesFromDictionary: (
NSDictionary*)otherDictionary;
Availability: OpenStep
Merges information from otherDictionary into the receiver. If a key exists in both dictionaries, the value from otherDictionary replaces that which was originally in the receiver.
- (id)
initWithCapacity: (unsigned)numItems;
Availability: OpenStep
This is a designated initialiser for the class.
Subclasses
should override this method.
Initializes an empty dictionary with memory preallocated for given number of entries. Although memory space will be grown as needed when entries are added, this can avoid the reallocate-and-copy process if the size of the ultimate contents is known in advance.
Calls
-init
(which does nothing but maintain MacOS-X compatibility), and needs to be re-implemented in subclasses in order to have all other initialisers work.
- (void)
removeAllObjects;
Availability: OpenStep
Clears out this dictionary by removing all entries.
- (void)
removeObjectForKey: (id)aKey;
Availability: OpenStep
Remove key-value mapping for given key aKey. No error if there is no mapping for the key. A warning will be generated if aKey is nil
.
- (void)
removeObjectsForKeys: (
NSArray*)keyArray;
Availability: OpenStep
Remove entries specified by the given keyArray. No error is generated if no mapping exists for a key or one is nil
, although a console warning is produced in the latter case.
- (void)
setDictionary: (
NSDictionary*)otherDictionary;
Availability: OpenStep
Remove all entries, then add all entries from otherDictionary.
- (void)
setObject: (id)anObject
forKey: (id)aKey;
Availability: OpenStep
Adds entry for
aKey, mapping to
anObject. If either is
nil
, an exception is raised. If
aKey already in dictionary, the value it maps to is silently replaced.
aKey and
anObject are both retained. (This differs from OS X, where the key is copied and must therefore implement the
<NSCopying>
protocol.)
- (void)
setValue: (id)value
forKey: (
NSString*)key;
Availability: MacOS-X 10.0.0
- (void)
takeStoredValue: (id)value
forKey: (
NSString*)key;
Availability: MacOS-X 10.0.0
- (void)
takeValue: (id)value
forKey: (
NSString*)key;
Availability: MacOS-X 10.0.0
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