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CFMutableString Reference

Derived from	CFString : CFPropertyList : CFType
Framework	CoreFoundation/CoreFoundation.h
Declared in	CFBase.h CFString.h
Companion guides	Property List Programming Topics for Core Foundation Strings Programming Guide for Core Foundation

Overview

CFMutableString manages dynamic strings. The basic interface for managing strings is provided by CFString. CFMutableString adds functions to modify the contents of a string.

CFMutableString is “toll-free bridged” with its Cocoa Foundation counterpart, NSMutableString. 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 NSMutableString * parameter, you can pass in a CFMutableStringRef, and in a function where you see a CFMutableStringRef parameter, you can pass in an NSMutableString instance. This also applies to concrete subclasses of NSMutableString. See Interchangeable Data Types for more information on toll-free bridging.

Functions

CFStringAppend

Appends the characters of a string to those of a CFMutableString object.

void CFStringAppend (
   CFMutableStringRef theString,
   CFStringRef appendedString
);

Parameters

theString: The string to which appendedString is appended. If theString is not a CFMutableString object, an assertion is raised.
appendedString: The string to append.

Discussion

This function reallocates the backing store of theString to accommodate the new length.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringAppendCharacters

Appends a buffer of Unicode characters to the character contents of a CFMutableString object.

void CFStringAppendCharacters (
   CFMutableStringRef theString,
   const UniChar *chars,
   CFIndex numChars
);

Parameters

theString: The string to which the characters in chars are appended.
chars: A pointer to a buffer of Unicode characters.
numChars: The number of Unicode characters in chars.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringAppendCString

Appends a C string to the character contents of a CFMutableString object.

void CFStringAppendCString (
   CFMutableStringRef theString,
   const char *cStr,
   CFStringEncoding encoding
);

Parameters

theString: The string to which the characters from cStr are appended. If this value is not a CFMutableString object, an assertion is raised.
cStr: A pointer to a C string buffer.
encoding: The encoding of the characters in cStr.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringAppendFormat

Appends a formatted string to the character contents of a CFMutableString object.

void CFStringAppendFormat (
   CFMutableStringRef theString,
   CFDictionaryRef formatOptions,
   CFStringRef format,
   ...
);

Parameters

theString: The string to which the formatted characters from format are appended. If this value is not a CFMutableString object, an assertion is raised.
formatOptions: A dictionary containing formatting options for the string (such as the thousand-separator character, which is dependent on locale). Currently, these options are an unimplemented feature.
format: A formatted string with printf-style specifiers.
...: Variable list of the values to be inserted in format.

Discussion

A formatted string is one with printf-style format specifiers embedded in the text such as %d (decimal), %f (double), and %@ (Core Foundation object). The subsequent arguments, in order, are substituted for the specifiers in the character data appended to theString. You can also reorder the arguments in the string by using modifiers of the form "n$" with the format specifiers (for example, %2$d).

For more information on supported specifiers, see the relevant section in Strings Programming Guide for Core Foundation.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringAppendFormatAndArguments

Appends a formatted string to the character contents of a CFMutableString object.

void CFStringAppendFormatAndArguments (
   CFMutableStringRef theString,
   CFDictionaryRef formatOptions,
   CFStringRef format,
   va_list arguments
);

Parameters

theString: The string to which the formatted characters from format are appended. If this value is not a CFMutableString object, an assertion is raised.
formatOptions: A dictionary containing formatting options for the string (such as the thousand-separator character, which is dependent on locale). Currently, these options are an unimplemented feature.
format: A formatted string with printf-style specifiers.
arguments: List of values to be inserted in format.

Discussion

For more information on supported specifiers, see the relevant section in Strings Programming Guide for Core Foundation.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringAppendPascalString

Appends a Pascal string to the character contents of a CFMutableString object.

void CFStringAppendPascalString (
   CFMutableStringRef theString,
   ConstStr255Param pStr,
   CFStringEncoding encoding
);

Parameters

theString: The string to which the characters in pStr are appended. If this value is not a CFMutableString object, an assertion is raised.
pStr: A Pascal string buffer.
encoding: The string encoding of the characters in pStr.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringCapitalize

Changes the first character in each word of a string to uppercase (if it is a lowercase alphabetical character).

void CFStringCapitalize (
   CFMutableStringRef theString,
   CFLocaleRef locale
);

Parameters

theString: The string to be capitalized. If this value is not a CFMutableString object, an assertion is raised.
locale: A locale that specifies a particular language or region. Prior to Mac OS X v10.3, this parameter was an untyped pointer and not used.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringCreateMutable

Creates an empty CFMutableString object.

CFMutableStringRef CFStringCreateMutable (
   CFAllocatorRef alloc,
   CFIndex maxLength
);

Parameters

alloc: The allocator to use to allocate memory for the new string. Pass NULL or kCFAllocatorDefault to use the current default allocator.
maxLength: The maximum number of Unicode characters that can be stored by the returned string. Pass 0 if there should be no character limit. Note that initially the string still has a length of 0; this parameter simply specifies what the maximum size is. CFMutableString might try to optimize its internal storage by paying attention to this value.

Return Value

A new empty CFMutableString object or NULL if there was a problem creating the object. Ownership follows the Create Rule.

Discussion

This function creates an empty (that is, content-less) CFMutableString object. You can add character data to this object with any of the CFStringAppend... functions, and thereafter you can insert, delete, replace, pad, and trim characters with the appropriate CFString functions. If the maxLength parameter is greater than 0, any attempt to add characters beyond this limit results in a run-time error.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringCreateMutableCopy

Creates a mutable copy of a string.

CFMutableStringRef CFStringCreateMutableCopy (
   CFAllocatorRef alloc,
   CFIndex maxLength,
   CFStringRef theString
);

Parameters

alloc: The allocator to use to allocate memory for the new string. Pass NULL or kCFAllocatorDefault to use the current default allocator.
maxLength: The maximum number of Unicode characters that can be stored by the returned object. Pass 0 if there should be no character limit. Note that initially the returned object still has the same length as the string argument; this parameter simply specifies what the maximum size is. CFString might try to optimize its internal storage by paying attention to this value.
theString: A string to copy.

Return Value

A string that has the same contents as theString. Returns NULL if there was a problem copying the object. Ownership follows the Create Rule.

Discussion

The returned mutable string is identical to the original string except for (perhaps) the mutability attribute. You can add character data to the returned string with any of the CFStringAppend... functions, and you can insert, delete, replace, pad, and trim characters with the appropriate CFString functions. If the maxLength parameter is greater than 0, any attempt to add characters beyond this limit results in a run-time error.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringCreateMutableWithExternalCharactersNoCopy

Creates a CFMutableString object whose Unicode character buffer is controlled externally.

CFMutableStringRef CFStringCreateMutableWithExternalCharactersNoCopy (
   CFAllocatorRef alloc,
   UniChar *chars,
   CFIndex numChars,
   CFIndex capacity,
   CFAllocatorRef externalCharactersAllocator
);

Parameters

alloc: The allocator to use to allocate memory for the string. Pass NULL or kCFAllocatorDefault to use the current default allocator.
chars: The Unicode character buffer for the new CFMutableString. Before calling, create this buffer on the stack or heap and optionally initialize it with Unicode character data. Upon return, the created CFString object keeps its own copy of the pointer to this buffer. You may pass in NULL if there is no initial buffer being provided.
numChars: The number of characters initially in the Unicode buffer pointed to by chars.
capacity: The capacity of the external buffer (chars); that is, the maximum number of Unicode characters that can be stored. This value should be 0 if no initial buffer is provided.
externalCharactersAllocator: The allocator to use to reallocate the external buffer when editing takes place and for deallocating the buffer when string is deallocated. If the default allocator is suitable for these purposes, pass NULL. If you do not want the new string to reallocate or deallocate memory for the buffer (that is, you assume responsibility for these things yourself), pass kCFAllocatorNull.

Return Value

A new mutable string, or NULL if there was a problem creating the object. Ownership follows the Create Rule.

Discussion

This function permits you to create a CFMutableString object whose backing store is an external Unicode character buffer—that is, a buffer that you control (or can control) entirely. This function allows you to take advantage of the features of CFString, particularly the CFMutableString functions that add and modify character data. But at the same time you can directly add, delete, modify, and examine the characters in the buffer. You can even replace the buffer entirely. If, however, you directly modify or replace the character buffer, you should inform the CFString object of this change with the CFStringSetExternalCharactersNoCopy function.

If you mutate the character contents with the CFString functions, and the buffer needs to be enlarged, the CFString object calls the allocation callbacks specified for the allocator externalCharactersAllocator.

This function should be used in special circumstances where you want to create a CFString wrapper around an existing, potentially large UniChar buffer you own. Using this function causes the CFString object to forgo some of its internal optimizations, so it should be avoided in general use. That is, if you want to create a CFString object from a small UniChar buffer, and you don't need to continue owning the buffer, use one of the other creation functions (for instance CFStringCreateWithCharacters) instead.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringDelete

Deletes a range of characters in a string.

void CFStringDelete (
   CFMutableStringRef theString,
   CFRange range
);

Parameters

theString: A string from which characters are to be deleted.
range: The range of characters in theString to delete.

Discussion

The characters after the deleted range are adjusted to “fill in” the gap.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringFindAndReplace

Replaces all occurrences of a substring within a given range.

CFIndex CFStringFindAndReplace (
   CFMutableStringRef theString,
   CFStringRef stringToFind,
   CFStringRef replacementString,
   CFRange rangeToSearch,
   CFOptionFlags compareOptions
);

Parameters

theString: The string to modify.
stringToFind: The substring to search for in theString.
replacementString: The replacement string for stringToFind.
rangeToSearch: The range within which to search in theString.
compareOptions: Flags that select different types of comparisons, such as localized comparison, case-insensitive comparison, and non-literal comparison. If you want the default comparison behavior, pass 0. See CFStringCompareFlags for the available flags.

Return Value

The number of instances of stringToFind that were replaced.

Discussion

The possible values of compareOptions are combinations of the kCFCompareCaseInsensitive, kCFCompareBackwards, kCFCompareNonliteral, and kCFCompareAnchored constants.

The kCFCompareBackwards option can be used to replace a substring starting from the end, which could produce different results. For example, if the parameter theString is “AAAAA”, stringToFind is “AA”, and replacementString is “B”, then the result is normally “BBA”. However, if the kCFCompareBackwards constant is used, the result is “ABB.”

The kCFCompareAnchored option assures that only anchored but multiple instances are found (the instances must be consecutive at start or end). For example, if the parameter theString is “AAXAA”, stringToFind is “A”, and replacementString is “B”, then the result is normally “BBXBB.” However, if the kCFCompareAnchored constant is used, the result is “BBXAA.”

Availability

Available in Mac OS X v10.2 and later.

Related Sample Code

simpleJavaLauncher

Declared In

CFString.h

CFStringFold

Folds a given string into the form specified by optional flags.

void CFStringFold (
   CFMutableStringRef theString,
   CFOptionFlags theFlags,
   CFLocaleRef theLocale
);

Parameters

theString

The string which is to be folded. If this parameter is not a valid mutable CFString, the behavior is undefined.

theFlags

The equivalency flags which describes the character folding form. See “String Comparison Flags” in CFString Reference for possible values. Only those flags containing the word "insensitive" are recognized; other flags are ignored.

Folding with kCFCompareCaseInsensitive removes case distinctions in accordance with the mapping specified by ftp://ftp.unicode.org/Public/UNIDATA/CaseFolding.txt. Folding with kCFCompareDiacriticInsensitive removes distinctions of accents and other diacritics. Folding with kCFCompareWidthInsensitive removes character width distinctions by mapping characters in the range U+FF00-U+FFEF to their ordinary equivalents.

theLocale

The locale to use for the operation. NULL specifies the canonical locale (the return value from CFLocaleGetSystem).

The locale argument affects the case mapping algorithm. For example, for the Turkish locale, case-insensitive compare matches “I” to “ı” (Unicode code point U+0131, Latin Small Dotless I), not the normal “i” character.

Discussion

Character foldings are operations that convert any of a set of characters sharing similar semantics into a single representative from that set.

You can use this function to preprocess strings that are to be compared, searched, or indexed. Note that folding does not include normalization, so you must use CFStringNormalize in addition to CFStringFold in order to obtain the effect of kCFCompareNonliteral.

Availability

Available in Mac OS X v10.5 and later.

Related Sample Code

DerivedProperty

Declared In

CFString.h

CFStringInsert

Inserts a string at a specified location in the character buffer of a CFMutableString object.

void CFStringInsert (
   CFMutableStringRef str,
   CFIndex idx,
   CFStringRef insertedStr
);

Parameters

str: The string to be modified. If this value is not a CFMutableString object, an assertion is raised.
index: The index of the character in str after which the new characters are to be inserted. If the index is out of bounds, an assertion is raised.
insertedStr: The string to insert into str.

Discussion

To accommodate the new characters, this function moves any existing characters to the right of the inserted characters the appropriate number of positions.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringLowercase

Changes all uppercase alphabetical characters in a CFMutableString to lowercase.

void CFStringLowercase (
   CFMutableStringRef theString,
   CFLocaleRef locale
);

Parameters

theString

The string to be lowercased. If this value is not a CFMutableString object, an assertion is raised.

locale

The locale to use when the lowercasing operation is performed. Prior to Mac OS X v10.3 this parameter was an untyped pointer and not used.

Special Considerations

The locale parameter type changed from void * to CFLocaleRef in Mac OS X v10.3.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringNormalize

Normalizes the string into the specified form as described in Unicode Technical Report #15.

void CFStringNormalize (
   CFMutableStringRef theString,
   CFStringNormalizationForm theForm
);

Parameters

theString: The string to be normalized.
theForm: The form to normalize theString.

Availability

Available in Mac OS X v10.2 and later.

Related Sample Code

Declared In

CFString.h

CFStringPad

Enlarges a string, padding it with specified characters, or truncates the string.

void CFStringPad (
   CFMutableStringRef theString,
   CFStringRef padString,
   CFIndex length,
   CFIndex indexIntoPad
);

Parameters

theString: The string to modify.
padString: A string containing the characters with which to fill the extended character buffer. Pass NULL to truncate the string.
length: The new length of theString. If this length is greater than the current length, padding takes place; if it is less, truncation takes place.
indexIntoPad: The index of the character in padString with which to begin padding. If you are truncating the string represented by the object, this parameter is ignored.

Discussion

This function has two purposes. It either enlarges the character buffer of a CFMutableString object to a given length, padding the added length with a given character or characters, or it truncates the character buffer to a smaller size. The key parameter for this behavior is length; if it is greater than the current length of the represented string, padding takes place, and if it less than the current length, truncation occurs.

For example, say you have a string, aMutStr, containing the characters "abcdef". The call

CFStringPad(aMutStr, CFSTR("123"), 9, 1);

results in aMutStr containing "abcdef231". However, the following call

CFStringPad(aMutStr, NULL, 3, 0);

results in aMutStr containing "abc".

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringReplace

Replaces part of the character contents of a CFMutableString object with another string.

void CFStringReplace (
   CFMutableStringRef theString,
   CFRange range,
   CFStringRef replacement
);

Parameters

theString: The string to modify. The characters are adjusted left or right (depending on the length of the substituted string) and the character buffer of the object is resized accordingly. If this value is not a CFMutableString object, an assertion is raised.
range: The range of characters in theString to replace.
replacement: The replacement string to put into theString.

Discussion

Although you can use this function to replace all characters in a CFMutableString object (by specifying a range of (0, CFStringGetLength(theString)) ), it is more convenient to use the CFStringReplaceAll function for that purpose.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringReplaceAll

Replaces all characters of a CFMutableString object with other characters.

void CFStringReplaceAll (
   CFMutableStringRef theString,
   CFStringRef replacement
);

Parameters

theString: The string to modify. If this value is not a CFMutableString object, an assertion is raised.
replacement: The replacement string to put into theString.

Discussion

The character buffer of theString is resized according to the length of the new characters.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

Declared In

CFString.h

CFStringSetExternalCharactersNoCopy

Notifies a CFMutableString object that its external backing store of Unicode characters has changed.

void CFStringSetExternalCharactersNoCopy (
   CFMutableStringRef theString,
   UniChar *chars,
   CFIndex length,
   CFIndex capacity
);

Parameters

theString: The string to act as a “wrapper” for the external backing store (chars). If this value is not a CFMutableString object, an assertion is raised.
chars: The external (client-owned) Unicode buffer acting as the backing store for theString.
length: The current length of the contents of chars (in Unicode characters).
capacity: The capacity of the Unicode buffer—that is, the total number of Unicode characters that can be stored in it before the buffer has to be grown.

Discussion

You use this function to reallocate memory for a string, if necessary, and change its references to the data in the buffer. The object must have been created with the CFStringCreateMutableWithExternalCharactersNoCopy function; see the discussion of this function for more information.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringTransform

Perform in-place transliteration on a mutable string.

Boolean CFStringTransform (
   CFMutableStringRef string,
   CFRange *range,
   CFStringRef transform,
   Boolean reverse
);

Parameters

string: The string to transform.
range: A pointer to the range over which the transformation is applied. NULL causes the whole string to be transformed. On return, range is modified to reflect the new range corresponding to the original range.
transform: A CFString object that identifies the transformation to apply. For a list of valid values, see “Transform Identifiers for CFStringTransform.” On Mac OS X v10.4 and later, you can also use any valid ICU transform ID defined in the ICU User Guide for Transforms.
reverse: A Boolean that, if true, specifies that the inverse transform should be used (if it exists).

Return Value

true if the transform is successful; otherwise false.

Discussion

The transformation represented by transform is applied to the given range of string, modifying it in place. Only the specified range is modified, but the transform may look at portions of the string outside that range for context. Reasons that the transform may be unsuccessful include an invalid transform identifier, and attempting to reverse an irreversible transform.

Availability

Available in Mac OS X v10.4 and later.

Declared In

CFString.h

CFStringTrim

Trims a specified substring from the beginning and end of a CFMutableString object.

void CFStringTrim (
   CFMutableStringRef theString,
   CFStringRef trimString
);

Parameters

theString: The string to trim. If this value is not a CFMutableString object, an assertion is raised.
trimString: The string to trim from theString. The characters of the trim string are treated as a substring and not individually; for example, if the mutable characters are "abc X" and the trim string is "XY", the mutable characters are not affected.

Availability

Available in Mac OS X v10.0 and later.

Related Sample Code

MoreSCF

Declared In

CFString.h

CFStringTrimWhitespace

Trims whitespace from the beginning and end of a CFMutableString object.

void CFStringTrimWhitespace (
   CFMutableStringRef theString
);

Parameters

theString: The string to trim. If this value is not a CFMutableString object, an assertion is raised.

Discussion

Whitespace for this function includes space characters, tabs, newlines, carriage returns, and any similar characters that do not have a visible representation.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

CFStringUppercase

Changes all lowercase alphabetical characters in a CFMutableString object to uppercase.

void CFStringUppercase (
   CFMutableStringRef theString,
   CFLocaleRef locale
);

Parameters

theString

The string to uppercase. If this value is not a CFMutableString object, an assertion is raised.

locale

A CFLocale object that specifies a particular language or region. Prior to Mac OS X v10.3, this parameter was an untyped pointer and not used.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFString.h

Data Types

CFMutableStringRef

A reference to a CFMutableString object.

typedef CFStringRef CFMutableStringRef;

Discussion

The type refers to a CFMutableString object, which “encapsulates” a Unicode string along with its length; the object has the attribute of being mutable, which means that its character contents can be modified. CFString is an opaque type that defines the characteristics and behavior of CFString objects, both immutable and mutable.

CFMutableString derives from CFString. Therefore, you can pass CFMutableString objects into functions accepting CFString objects.

Availability

Available in Mac OS X v10.0 and later.

Declared In

CFBase.h

Constants

String Normalization Forms

Unicode normalization forms as described in Unicode Technical Report #15.

enum CFStringNormalizationForm {
   kCFStringNormalizationFormD = 0,
   kCFStringNormalizationFormKD = 1,
   kCFStringNormalizationFormC = 2,
   kCFStringNormalizationFormKC = 3
};
typedef enum CFStringNormalizationForm CFStringNormalizationForm;

Constants

kCFStringNormalizationFormD

Canonical decomposition.

Available in Mac OS X v10.2 and later.

Declared in CFString.h.

kCFStringNormalizationFormKD

Compatibility decomposition.

Available in Mac OS X v10.2 and later.

Declared in CFString.h.

kCFStringNormalizationFormC

Canonical decomposition followed by canonical composition.

Available in Mac OS X v10.2 and later.

Declared in CFString.h.

kCFStringNormalizationFormKC

Compatibility decomposition followed by canonical composition.

Available in Mac OS X v10.2 and later.

Declared in CFString.h.

Transform Identifiers for CFStringTransform

Constants that identify transforms used with CFStringTransform.

const CFStringRef kCFStringTransformStripCombiningMarks;
const CFStringRef kCFStringTransformToLatin;
const CFStringRef kCFStringTransformFullwidthHalfwidth;
const CFStringRef kCFStringTransformLatinKatakana;
const CFStringRef kCFStringTransformLatinHiragana;
const CFStringRef kCFStringTransformHiraganaKatakana;
const CFStringRef kCFStringTransformMandarinLatin;
const CFStringRef kCFStringTransformLatinHangul;
const CFStringRef kCFStringTransformLatinArabic;
const CFStringRef kCFStringTransformLatinHebrew;
const CFStringRef kCFStringTransformLatinThai;
const CFStringRef kCFStringTransformLatinCyrillic;
const CFStringRef kCFStringTransformLatinGreek;
const CFStringRef kCFStringTransformToXMLHex;
const CFStringRef kCFStringTransformToUnicodeName;
const CFStringRef kCFStringTransformStripDiacritics;