| Derived from | |
| Framework | CoreFoundation/CoreFoundation.h |
| Declared in | CFData.h |
| Companion guides |
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 Interchangeable Data Types for more information on toll-free bridging.
Appends the bytes from a byte buffer to the contents of a CFData object.
void CFDataAppendBytes ( CFMutableDataRef theData, const UInt8 *bytes, CFIndex length );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
A pointer to the buffer of bytes to be added to theData.
The number of bytes in the byte buffer bytes.
CFData.hCreates an empty CFMutableData object.
CFMutableDataRef CFDataCreateMutable ( CFAllocatorRef allocator, CFIndex capacity );
The CFAllocator object to be used to allocate memory for the new object. Pass NULL or kCFAllocatorDefault to use the current default allocator.
The maximum number of bytes that the CFData object can contain. The CFData object starts empty and can grow to contain this number of values (and it can have less).
Pass 0 to specify that the maximum capacity is not limited. The value must not be negative.
A CFMutableData object or NULL if there was a problem creating the object. Ownership follows the Create Rule.
This function creates an empty (that is, content-less) CFMutableData object. You can add raw data to this object with the CFDataAppendBytes function, and thereafter you can replace and delete characters with the appropriate CFMutableData functions. If the capacity parameter is greater than 0, any attempt to add characters beyond this limit can result in undefined behavior.
CFData.hCreates a CFMutableData object by copying another CFData object.
CFMutableDataRef CFDataCreateMutableCopy ( CFAllocatorRef allocator, CFIndex capacity, CFDataRef theData );
The CFAllocator object to be used to allocate memory for the new object. Pass NULL or kCFAllocatorDefault to use the current default allocator.
The maximum number of bytes that the CFData object can contain. The CFData object starts with the same length as the original object, and can grow to contain this number of bytes.
Pass 0 to specify that the maximum capacity is not limited. If non-0, capacity must be greater than or equal to the length of theData.
The CFData object to be copied.
A CFMutableData object that has the same contents as the original object. Returns NULL if there was a problem copying the object. Ownership follows the Create Rule.
CFData.hDeletes the bytes in a CFMutableData object within a specified range.
void CFDataDeleteBytes ( CFMutableDataRef theData, CFRange range );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
The range of bytes (that is, the starting byte and the number of bytes from that point) to delete from theData's byte buffer.
CFData.hReturns a pointer to a mutable byte buffer of a CFMutableData object.
UInt8 *CFDataGetMutableBytePtr ( CFMutableDataRef theData );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
A pointer to the bytes associated with theData.
If the length of theData’s data is not zero, this function is guaranteed to return a pointer to a CFMutableData object's internal bytes. If the length of theData’s data is zero, this function may or may not return NULL dependent upon many factors related to how the object was created (moreover, in this case the function result might change between different releases and on different platforms).
CFData.hIncreases the length of a CFMutableData object's internal byte buffer, zero-filling the extension to the buffer.
void CFDataIncreaseLength ( CFMutableDataRef theData, CFIndex extraLength );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
The number of bytes by which to increase the byte buffer.
This function increases the length of a CFMutableData object’s underlying byte buffer to a new size, initializing the new bytes to 0.
CFData.hReplaces 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 );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
The range of bytes (that is, the starting byte and the number of bytes from that point) to delete from theData's byte buffer.
A pointer to the buffer containing the replacement bytes.
The number of bytes in the byte buffer newBytes.
CFData.hResets the length of a CFMutableData object's internal byte buffer.
void CFDataSetLength ( CFMutableDataRef theData, CFIndex length );
A CFMutableData object. If you pass an immutable CFData object, the behavior is not defined.
The new size of theData’s byte buffer.
This function resets the length of a CFMutableData object’s underlying byte buffer to a new size. If that size is less than the current size, it truncates the excess bytes. If that size is greater than the current size, it zero-fills the extension to the byte buffer.
CFData.hA reference to a CFMutableData object.
typedef struct __CFData *CFMutableDataRef;
CFData.hLast updated: 2009-11-17
Mac OS X Reference Library Data Management: Data Types & Collections CFMutableData Reference