Copies the character contents of a string to a local C string buffer after converting the characters to a given encoding.


func CFStringGetCString(_ theString: CFString!, _ buffer: UnsafeMutablePointer<Int8>!, _ bufferSize: CFIndex, _ encoding: CFStringEncoding) -> Bool



The string whose contents you wish to access.


The C string buffer into which to copy the string. On return, the buffer contains the converted characters. If there is an error in conversion, the buffer contains only partial results.

The buffer must be large enough to contain the converted characters and a NUL terminator. For example, if the string is Toby, the buffer must be at least 5 bytes long.


The length of buffer in bytes.


The string encoding to which the character contents of theString should be converted. The encoding must specify an 8-bit encoding.

Return Value

true upon success or false if the conversion fails or the provided buffer is too small.


This function is useful when you need your own copy of a string’s character data as a C string. You also typically call it as a “backup” when a prior call to the CFStringGetCStringPtr(_:_:) function fails.

See Also

Accessing Characters

func CFStringCreateExternalRepresentation(CFAllocator!, CFString!, CFStringEncoding, UInt8) -> CFData!

Creates an “external representation” of a CFString object, that is, a CFData object.

func CFStringGetBytes(CFString!, CFRange, CFStringEncoding, UInt8, Bool, UnsafeMutablePointer<UInt8>!, CFIndex, UnsafeMutablePointer<CFIndex>!) -> CFIndex

Fetches a range of the characters from a string into a byte buffer after converting the characters to a specified encoding.

func CFStringGetCharacterAtIndex(CFString!, CFIndex) -> UniChar

Returns the Unicode character at a specified location in a string.

func CFStringGetCharacters(CFString!, CFRange, UnsafeMutablePointer<UniChar>!)

Copies a range of the Unicode characters from a string to a user-provided buffer.

func CFStringGetCharactersPtr(CFString!) -> UnsafePointer<UniChar>!

Quickly obtains a pointer to the contents of a string as a buffer of Unicode characters.

func CFStringGetCharacterFromInlineBuffer(UnsafeMutablePointer<CFStringInlineBuffer>!, CFIndex) -> UniChar

Returns the Unicode character at a specific location in an in-line buffer.

func CFStringGetCStringPtr(CFString!, CFStringEncoding) -> UnsafePointer<Int8>!

Quickly obtains a pointer to a C-string buffer containing the characters of a string in a given encoding.

func CFStringGetLength(CFString!) -> CFIndex

Returns the number (in terms of UTF-16 code pairs) of Unicode characters in a string.

func CFStringGetPascalString(CFString!, StringPtr!, CFIndex, CFStringEncoding) -> Bool

Copies the character contents of a CFString object to a local Pascal string buffer after converting the characters to a requested encoding.

func CFStringGetPascalStringPtr(CFString!, CFStringEncoding) -> ConstStringPtr!

Quickly obtains a pointer to a Pascal buffer containing the characters of a string in a given encoding.

func CFStringGetRangeOfComposedCharactersAtIndex(CFString!, CFIndex) -> CFRange

Returns the range of the composed character sequence at a specified index.

func CFStringInitInlineBuffer(CFString!, UnsafeMutablePointer<CFStringInlineBuffer>!, CFRange)

Initializes an in-line buffer to use for efficient access of a CFString object's characters.

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