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CFArray Reference

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

Overview

CFArray and its derived mutable type, CFMutableArray, manage ordered collections of values called arrays. CFArray creates static arrays and CFMutableArray creates dynamic arrays.

You create a static array object using either the CFArrayCreate or CFArrayCreateCopy function. These functions return an array containing the values you pass in as arguments. (Note that arrays can’t contain NULL pointers; in most cases, though, you can use the kCFNull constant instead.) Values are not copied but retained using the retain callback provided when an array was created. Similarly, when a value is removed from an array, it is released using the release callback.

CFArray’s two primitive functions CFArrayGetCount and CFArrayGetValueAtIndex provide the basis for all other functions in its interface. The CFArrayGetCount function returns the number of elements in an array; CFArrayGetValueAtIndex gives you access to an array’s elements by index, with index values starting at 0.

A number of CFArray functions allow you to operate over a range of values in an array, for example CFArrayApplyFunction lets you apply a function to values in an array, and CFArrayBSearchValues searches an array for the value that matches its parameter. Recall that a range is defined as {start, length}, therefore to operate over the entire array the range you supply should be {0, N} (where N is the count of the array).

CFArray is “toll-free bridged” with its Cocoa Foundation counterpart, NSArray. This means that the Core Foundation type is interchangeable in function or method calls with the bridged Foundation object. Therefore, in a method where you see an NSArray * parameter, you can pass in a CFArrayRef, and in a function where you see a CFArrayRef parameter, you can pass in an NSArray instance. This also applies to concrete subclasses of NSArray. See Interchangeable Data Types for more information on toll-free bridging.

Functions by Task

Creating an Array

Examining an Array

Applying a Function to Elements

Getting the CFArray Type ID

Functions

CFArrayApplyFunction

Calls a function once for each element in range in an array.

void CFArrayApplyFunction (
   CFArrayRef theArray,
   CFRange range,
   CFArrayApplierFunction applier,
   void *context
);

Parameters
theArray

The array to whose elements to apply the function.

range

The range of values within theArray to which to apply the applier function. The range must not exceed the bounds of theArray. The range may be empty (length 0).

applier

The callback function to call once for each value in the given range in theArray. If there are values in the range that the applier function does not expect or cannot properly apply to, the behavior is undefined.

context

A pointer-sized program-defined value, which is passed as the second argument to the applier function, but is otherwise unused by this function. If the context is not what is expected by the applier function, the behavior is undefined.

Discussion

While this function iterates over a mutable collection, it is unsafe for the applier function to change the contents of the collection.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayBSearchValues

Searches an array for a value using a binary search algorithm.

CFIndex CFArrayBSearchValues (
   CFArrayRef theArray,
   CFRange range,
   const void *value,
   CFComparatorFunction comparator,
   void *context
);

Parameters
theArray

An array, sorted from least to greatest according to the comparator function.

range

The range within theArray to search. The range must not exceed the bounds of theArray. The range may be empty (length 0).

value

The value for which to find a match in theArray. If value, or any other value in theArray, is not understood by the comparator callback, the behavior is undefined.

comparator

The function with the comparator function type signature that is used in the binary search operation to compare values in theArray with the given value. If there are values in the range that the comparator function does not expect or cannot properly compare, the behavior is undefined.

context

A pointer-sized program-defined value, which is passed as the third argument to the comparator function, but is otherwise unused by this function. If the context is not what is expected by the comparator function, the behavior is undefined.

Return Value

The return value is one of the following:

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayContainsValue

Reports whether or not a value is in an array.

Boolean CFArrayContainsValue (
   CFArrayRef theArray,
   CFRange range,
   const void *value
);

Parameters
theArray

The array to search.

range

The range within theArray to search. The range must not exceed the bounds of theArray). The range may be empty (length 0).

value

The value to match in theArray. The equal callback provided when theArray was created is used to compare. If the equal callback was NULL, pointer equality (in C, ==) is used. If value, or any other value in theArray, is not understood by the equal callback, the behavior is undefined.

Return Value

true, if value is in the specified range of theArray, otherwise false.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayCreate

Creates a new immutable array with the given values.

CFArrayRef CFArrayCreate (
   CFAllocatorRef allocator,
   const void **values,
   CFIndex numValues,
   const CFArrayCallBacks *callBacks
);

Parameters
allocator

The allocator to use to allocate memory for the new array and its storage for values. Pass NULL or kCFAllocatorDefault to use the current default allocator.

values

A C array of the pointer-sized values to be in the new array. The values in the new array are ordered in the same order in which they appear in this C array. This value may be NULL if numValues is 0. This C array is not changed or freed by this function. If values is not a valid pointer to a C array of at least numValues elements, the behavior is undefined.

numValues

The number of values to copy from the values C array into the new array. This number will be the count of the new array—it must not be negative or greater than the number of elements in values.

callBacks

A pointer to a CFArrayCallBacks structure initialized with the callbacks for the array to use on each value in the collection. The retain callback is used within this function, for example, to retain all of the new values from the values C array. 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 if a valid structure of version 0 with all fields NULL had been passed in. 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 CFArrayCallBacks 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 collection contains only CFType objects, then pass kCFTypeArrayCallBacks to use the default callback functions.

Return Value

A new immutable array containing numValues from values, or NULL if there was a problem creating the object. Ownership follows the Create Rule.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayCreateCopy

Creates a new immutable array with the values from another array.

CFArrayRef CFArrayCreateCopy (
   CFAllocatorRef allocator,
   CFArrayRef theArray
);

Parameters
allocator

The allocator to use to allocate memory for the new array and its storage for values. Pass NULL or kCFAllocatorDefault to use the current default allocator.

theArray

The array to copy.

Return Value

A new CFArray object that contains the same values as theArray. Ownership follows the Create Rule.

Discussion

The pointer values from theArray are copied into the new array; the values are also retained by the new array. The count of the new array is the same as theArray. The new array uses the same callbacks as theArray.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayGetCount

Returns the number of values currently in an array.

CFIndex CFArrayGetCount (
   CFArrayRef theArray
);

Parameters
theArray

The array to examine.

Return Value

The number of values in theArray.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayGetCountOfValue

Counts the number of times a given value occurs in an array.

CFIndex CFArrayGetCountOfValue (
   CFArrayRef theArray,
   CFRange range,
   const void *value
);

Parameters
theArray

The array to examine.

range

The range within theArray to search. The range must lie within the bounds of theArray). The range may be empty (length 0).

value

The value for which to find matches in theArray. The equal callback provided when theArray was created is used to compare. If the equal callback was NULL, pointer equality (in C, ==) is used. If value, or any other value in theArray, is not understood by the equal callback, the behavior is undefined.

Return Value

The number of times value occurs in theArray, within the specified range.

Availability
Declared In
CFArray.h

CFArrayGetFirstIndexOfValue

Searches an array forward for a value.

CFIndex CFArrayGetFirstIndexOfValue (
   CFArrayRef theArray,
   CFRange range,
   const void *value
);

Parameters
theArray

The array to examine.

range

The range within theArray to search. The range must lie within the bounds of theArray. The range may be empty (length 0). The search progresses from the lowest index defined by the range to the highest.

value

The value for which to find a match in theArray. The equal callback provided when theArray was created is used to compare. If the equal callback was NULL, pointer equality (in C, ==) is used. If value, or any other value in theArray, is not understood by the equal callback, the behavior is undefined.

Return Value

The lowest index of the matching values in the range, or -1 if no value in the range matched.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayGetLastIndexOfValue

Searches an array backward for a value.

CFIndex CFArrayGetLastIndexOfValue (
   CFArrayRef theArray,
   CFRange range,
   const void *value
);

Parameters
theArray

The array to examine.

range

The range within theArray to search. The range must not exceed the bounds of theArray. The range may be empty (length 0). The search progresses from the highest index defined by the range to the lowest.

value

The value for which to find a match in theArray. The equal callback provided when theArray was created is used to compare. If the equal callback was NULL, pointer equality (in C, ==) is used. If value, or any other value in theArray, is not understood by the equal callback, the behavior is undefined.

Return Value

The highest index of the matching values in the range, or -1 if no value in the range matched.

Availability
Declared In
CFArray.h

CFArrayGetTypeID

Returns the type identifier for the CFArray opaque type.

CFTypeID CFArrayGetTypeID (
   void
);

Return Value

The type identifier for the CFArray opaque type.

Special Considerations

CFMutableArray objects have the same type identifier as CFArray objects.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayGetValueAtIndex

Retrieves a value at a given index.

const void * CFArrayGetValueAtIndex (
   CFArrayRef theArray,
   CFIndex idx
);

Parameters
theArray

The array to examine.

idx

The index of the value to retrieve. If the index is outside the index space of theArray (0 to N-1 inclusive (where N is the count of theArray), the behavior is undefined.

Return Value

The value at the idx index in theArray. If the return value is a Core Foundation Object, ownership follows the Get Rule.

Availability
Related Sample Code
Declared In
CFArray.h

CFArrayGetValues

Fills a buffer with values from an array.

void CFArrayGetValues (
   CFArrayRef theArray,
   CFRange range,
   const void **values
);

Parameters
theArray

The array to examine.

range

The range of values within theArray to retrieve. The range must lie within the bounds of theArray. The range may be empty (length 0), in which case no values are put into the buffer values.

values

A C array of pointer-sized values to be filled with values from theArray. The values in the C array are in the same order as they appear in theArray. If this value is not a valid pointer to a C array of at least range.length pointers, the behavior is undefined. If the values are Core Foundation objects, ownership follows the Get Rule.

Availability
Related Sample Code
Declared In
CFArray.h

Callbacks

CFArrayApplierFunction

Prototype of a callback function that may be applied to every value in an array.

typedef void (*CFArrayApplierFunction) (
   const void *value,
   void *context
);

If you name your function MyCallBack, you would declare it like this:

void MyCallBack (
   const void *value,
   void *context
);

Parameters
value

The current value in an array.

context

The program-defined context parameter given to the applier function.

Discussion

This callback is passed to the CFArrayApplyFunction function, which iterates over the values in an array and applies the behavior defined in the applier function to each value in an array.

Availability
Declared In
CFArray.h

CFArrayCopyDescriptionCallBack

Prototype of a callback function used to get a description of a value in an array.

typedef CFStringRef (*CFArrayCopyDescriptionCallBack) (
   const void *value
);

If you name your function MyCallBack, you would declare it like this:

CFStringRef MyCallBack (
   const void *value
);

Parameters
value

The value to be described.

Return Value

A textual description of value. The caller is responsible for releasing this object.

Discussion

This callback is passed to CFArrayCreate in a CFArrayCallBacks structure. This callback is used by the CFCopyDescription function.

Availability
Declared In
CFArray.h

CFArrayEqualCallBack

Prototype of a callback function used to determine if two values in an array are equal.

typedef Boolean (*CFArrayEqualCallBack) (
   const void *value1,
   const void *value2
);

If you name your function MyCallBack, you would declare it like this:

Boolean MyCallBack (
   const void *value1,
   const void *value2
);

Parameters
value1

A value in an array to be compared with value2 for equality.

value2

A value in an array to be compared with value1 for equality.

Return Value

true if value1 and value2 are equal, false otherwise.

Discussion

This callback is passed to CFArrayCreate in a CFArrayCallBacks structure.

Availability
Declared In
CFArray.h

CFArrayReleaseCallBack

Prototype of a callback function used to release a value before it’s removed from an array.

typedef void (*CFArrayReleaseCallBack) (
   CFAllocatorRef allocator,
   const void *value
);

If you name your function MyCallBack, you would declare it like this:

void MyCallBack (
   CFAllocatorRef allocator,
   const void *value
);

Parameters
allocator

The array’s allocator.

value

The value being removed from an array.

Discussion

This callback is passed to CFArrayCreate in a CFArrayCallBacks structure.

Availability
Declared In
CFArray.h

CFArrayRetainCallBack

Prototype of a callback function used to retain a value being added to an array. 

typedef const void *(*CFArrayRetainCallBack) (
   CFAllocatorRef allocator,
   const void *value
);

If you name your function MyCallBack, you would declare it like this:

const void *MyCallBack (
   CFAllocatorRef allocator,
   const void *value
);

Parameters
allocator

The array’s allocator.

value

The value being added to an array.

Return Value

The value to store in an array, which is usually the value parameter passed to this callback, but may be a different value if a different value should be stored in an array.

Discussion

This callback is passed to CFArrayCreate in a CFArrayCallBacks structure.

Availability
Declared In
CFArray.h

Data Types

CFArrayCallBacks

Structure containing the callbacks of a CFArray.

struct CFArrayCallBacks {
   CFIndex version;
   CFArrayRetainCallBack retain;
   CFArrayReleaseCallBack release;
   CFArrayCopyDescriptionCallBack copyDescription;
   CFArrayEqualCallBack equal;
};
typedef struct CFArrayCallBacks CFArrayCallBacks;

Fields
version

The version number of this structure. If not one of the defined version numbers for this opaque type, the behavior is undefined. The current version of this structure is 0.

retain

The callback used to retain each value as they are added to the collection. If NULL, values are not retained. See CFArrayRetainCallBack for a description of this callback.

release

The callback used to release values as they are removed from the collection. If NULL, values are not released. See CFArrayReleaseCallBack for a description of this callback.

copyDescription

The callback used to create a descriptive string representation of each value in the collection. If NULL, the collection will create a simple description of each value. See CFArrayCopyDescriptionCallBack for a description of this callback.

equal

The callback used to compare values in the array for equality for some operations. If NULL, the collection will use pointer equality to compare values in the collection. See CFArrayEqualCallBack for a description of this callback.

Availability
Declared In
CFArray.h

CFArrayRef

A reference to an immutable array object.

typedef const struct __CFArray *CFArrayRef;

Availability
Declared In
CFArray.h

Constants

Predefined Callback Structures

CFArray provides some predefined callbacks for your convenience.

const CFArrayCallBacks kCFTypeArrayCallBacks;

Constants
kCFTypeArrayCallBacks

Predefined CFArrayCallBacks structure containing a set of callbacks appropriate for use when the values in a CFArray are all CFType-derived objects. The retain callback is CFRetain, the release callback is CFRelease, the copy callback is CFCopyDescription, and the equal callback is CFEqual. Therefore, if you use this constant when creating the collection, items are automatically retained when added to the collection, and released when removed from the collection.

Available in Mac OS X v10.0 and later.

Declared in CFArray.h.



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© 2003, 2007 Apple Inc. All Rights Reserved. (Last updated: 2007-05-22)

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