CFMutableData Reference

Overview

CFMutableData manages dynamic binary data. The basic interface for managing binary data is provided by CFData. CFMutableData adds functions to modify the contents of a binary data object.

You create a mutable data object using either the CFDataCreateMutable or CFDataCreateMutableCopy function.

Bytes are added to a data object with the CFDataAppendBytes function. Bytes are removed from a data object with the CFDataDeleteBytes function.

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

Functions by Task

Creating a Mutable Data Object

• CFDataCreateMutable
• CFDataCreateMutableCopy

Accessing Data

• CFDataGetMutableBytePtr

Modifying a Mutable Data Object

• CFDataAppendBytes
• CFDataDeleteBytes
• CFDataReplaceBytes
• CFDataIncreaseLength
• CFDataSetLength

Functions

CFDataAppendBytes

Appends the bytes from a byte buffer to the contents of a CFData object.

void CFDataAppendBytes (
   CFMutableDataRef theData,
   const UInt8 *bytes,
   CFIndex length
);

CFDataCreateMutable

Creates an empty CFMutableData object.

CFMutableDataRef CFDataCreateMutable (
   CFAllocatorRef allocator,
   CFIndex capacity
);

CFDataCreateMutableCopy

Creates a CFMutableData object by copying another CFData object.

CFMutableDataRef CFDataCreateMutableCopy (
   CFAllocatorRef allocator,
   CFIndex capacity,
   CFDataRef theData
);

CFDataDeleteBytes

Deletes the bytes in a CFMutableData object within a specified range.

void CFDataDeleteBytes (
   CFMutableDataRef theData,
   CFRange range
);

CFDataGetMutableBytePtr

Returns a pointer to a mutable byte buffer of a CFMutableData object.

UInt8 *CFDataGetMutableBytePtr (
   CFMutableDataRef theData
);

CFDataIncreaseLength

Increases the length of a CFMutableData object's internal byte buffer, zero-filling the extension to the buffer.

void CFDataIncreaseLength (
   CFMutableDataRef theData,
   CFIndex extraLength
);

CFDataReplaceBytes

Replaces those bytes in a CFMutableData object that fall within a specified range with other bytes.

void CFDataReplaceBytes (
   CFMutableDataRef theData,
   CFRange range,
   const UInt8 *newBytes,
   CFIndex newLength
);

CFDataSetLength

Resets the length of a CFMutableData object's internal byte buffer.

void CFDataSetLength (
   CFMutableDataRef theData,
   CFIndex length
);

Data Types

CFMutableDataRef

A reference to a CFMutableData object.

typedef struct __CFData *CFMutableDataRef;