CFMutableDictionary Reference

Derived from
Framework
CoreFoundation/CoreFoundation.h
Declared in
CFDictionary.h
Companion guides

Overview

CFMutableDictionary manages dynamic dictionaries. The basic interface for managing dictionaries is provided by CFDictionary Reference. CFMutableDictionary adds functions to modify the contents of a dictionary.

You create a mutable dictionary object using either the CFDictionaryCreateMutable or CFDictionaryCreateMutableCopy function. You can add key-value pairs using the CFDictionaryAddValue and CFDictionarySetValue functions. When adding key-value pairs to a dictionary, the keys and values are not copied—they are retained so they are not invalidated before the dictionary is deallocated. You can remove key-value pairs using the CFDictionaryRemoveValue function. When removing key-value pairs from a dictionary, the keys and values are released.

CFMutableDictionary is “toll-free bridged” with its Cocoa Foundation counterpart, NSMutableDictionary. What this means is that the Core Foundation type is interchangeable in function or method calls with the bridged Foundation object. This means that in a method where you see an NSMutableDictionary * parameter, you can pass in a CFMutableDictionaryRef, and in a function where you see a CFMutableDictionaryRef parameter, you can pass in an NSMutableDictionary instance. This also applies to concrete subclasses of NSMutableDictionary. See “Toll-Free Bridged Types” for more information on toll-free bridging.

Functions by Task

Creating a Mutable Dictionary

Modifying a Dictionary

Functions

CFDictionaryAddValue

Adds a key-value pair to a dictionary if the specified key is not already present.

void CFDictionaryAddValue (
   CFMutableDictionaryRef theDict,
   const void *key,
   const void *value
);
Parameters
theDict

The dictionary to modify. If the dictionary is a fixed-capacity dictionary and it is full before this operation, the behavior is undefined.

key

The key for the value to add to the dictionary—a CFType object or a pointer value. The key is retained by the dictionary using the retain callback provided when the dictionary was created, so must be of the type expected by the callback. If a key which matches key is already present in the dictionary, this function does nothing ("add if absent").

value

A CFType object or a pointer value to add to the dictionary. The value is retained by the dictionary using the retain callback provided when the dictionary was created, so must be of the type expected by the callback.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionaryCreateMutable

Creates a new mutable dictionary.

CFMutableDictionaryRef CFDictionaryCreateMutable (
   CFAllocatorRef allocator,
   CFIndex capacity,
   const CFDictionaryKeyCallBacks *keyCallBacks,
   const CFDictionaryValueCallBacks *valueCallBacks
);
Parameters
allocator

The allocator to use to allocate memory for the new dictionary and its storage for key-value pairs. Pass NULL or kCFAllocatorDefault to use the current default allocator.

capacity

The maximum number of key-value pairs that can be contained by the new dictionary. The dictionary starts empty and can grow to this number of key-value pairs (and it can have less).

Pass 0 to specify that the maximum capacity is not limited. The value must not be negative.

keyCallBacks

A pointer to a CFDictionaryKeyCallBacks structure initialized with the callbacks to use to retain, release, describe, and compare keys in the dictionary. A copy of the contents of the callbacks structure is made, so that a pointer to a structure on the stack can be passed in or can be reused for multiple collection creations.

This value may be NULL, which is treated as a valid structure of version 0 with all fields NULL. Otherwise, if any of the fields are not valid pointers to functions of the correct type, or this value is not a valid pointer to a CFDictionaryKeyCallBacks structure, the behavior is undefined. If any of the keys put into the collection is not one understood by one of the callback functions, the behavior when that callback function is used is undefined.

If the dictionary will contain only CFType objects, then pass a pointer to kCFTypeDictionaryKeyCallBacks as this parameter to use the default callback functions.

valueCallBacks

A pointer to a CFDictionaryValueCallBacks structure initialized with the callbacks to use to retain, release, describe, and compare values in the dictionary. A copy of the contents of the callbacks structure is made, so that a pointer to a structure on the stack can be passed in or can be reused for multiple collection creations.

This value may be NULL, which is treated as a valid structure of version 0 with all fields NULL. Otherwise, if any of the fields are not valid pointers to functions of the correct type, or this value is not a valid pointer to a CFDictionaryValueCallBacks structure, the behavior is undefined. If any value put into the collection is not one understood by one of the callback functions, the behavior when that callback function is used is undefined.

If the dictionary will contain CFType objects only, then pass a pointer to kCFTypeDictionaryValueCallBacks as this parameter to use the default callback functions.

Return Value

A new dictionary, or NULL if there was a problem creating the object. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionaryCreateMutableCopy

Creates a new mutable dictionary with the key-value pairs from another dictionary.

CFMutableDictionaryRef CFDictionaryCreateMutableCopy (
   CFAllocatorRef allocator,
   CFIndex capacity,
   CFDictionaryRef theDict
);
Parameters
allocator

The allocator to use to allocate memory for the new dictionary and its storage for key-value pairs. Pass NULL or kCFAllocatorDefault to use the current default allocator.

capacity

The maximum number of key-value pairs that can be contained by the new dictionary. The dictionary starts with the same number of key-value pairs as theDict and can grow to this number of values (and it can have less).

Pass 0 to specify that the maximum capacity is not limited. If non-0, capacity must be greater than or equal to the count of theDict.

theDict

The dictionary to copy. The keys and values from the dictionary are copied as pointers into the new dictionary, not that which the values point to (if anything). The keys and values are also retained by the new dictionary. The count of the new dictionary is the same as the count of theDict. The new dictionary uses the same callbacks as theDict.

Return Value

A new dictionary that contains the same values as theDict. Ownership follows the Create Rule in Memory Management Programming Guide for Core Foundation.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionaryRemoveAllValues

Removes all the key-value pairs from a dictionary, making it empty.

void CFDictionaryRemoveAllValues (
   CFMutableDictionaryRef theDict
);
Parameters
theDict

The dictionary to modify.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionaryRemoveValue

Removes a key-value pair.

void CFDictionaryRemoveValue (
   CFMutableDictionaryRef theDict,
   const void *key
);
Parameters
theDict

The dictionary to modify.

key

The key of the value to remove from theDict. If a key which matches key is present in theDict, the key-value pair is removed from the dictionary, otherwise this function does nothing ("remove if present").

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionaryReplaceValue

Replaces a value corresponding to a given key.

void CFDictionaryReplaceValue (
   CFMutableDictionaryRef theDict,
   const void *key,
   const void *value
);
Parameters
theDict

The dictionary to modify.

key

The key of the value to replace in theDict. If a key which matches key is present in the dictionary, the value is changed to the value, otherwise this function does nothing (“replace if present”).

value

The new value for key. The value object is retained by theDict using the retain callback provided when theDict was created, and the old value is released. value must be of the type expected by the retain and release callbacks.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

CFDictionarySetValue

Sets the value corresponding to a given key.

void CFDictionarySetValue (
   CFMutableDictionaryRef theDict,
   const void *key,
   const void *value
);
Parameters
theDict

The dictionary to modify. If this parameter is a fixed-capacity dictionary and it is full before this operation, and the key does not exist in the dictionary, the behavior is undefined.

key

The key of the value to set in theDict. If a key which matches key is already present in the dictionary, only the value for the key is changed ("add if absent, replace if present"). If no key matches key, the key-value pair is added to the dictionary.

If a key-value pair is added, both key and value are retained by the dictionary, using the retain callback provided when theDict was created. key must be of the type expected by the key retain callback.

value

The value to add to or replace in theDict. value is retained using the value retain callback provided when theDict was created, and the previous value if any is released. value must be of the type expected by the retain and release callbacks.

Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h

Data Types

CFMutableDictionaryRef

A reference to a mutable dictionary object.

typedef struct __CFDictionary *CFMutableDictionaryRef;
Availability
  • Available in OS X v10.0 and later.
Declared In
CFDictionary.h