Up
Authors
- Andrew Kachites McCallum (
mccallum@gnu.ai.mit.edu
)
-
- Richard Frith-Macdonald (
richard@brainstorm.co.uk
)
-
Version: 1.158
Date: 2005/11/06 13:53:39
Copyright: (C) 1995, 1996, 1997, 2000, 2002 Free Software Foundation, Inc.
- Declared in:
- Foundation/NSData.h
- Conforms to:
- NSCoding
- NSCopying
- NSMutableCopying
Availability: OpenStep
Class for storing a byte array. Methods for initializing from memory a file, or the network are provided, as well as the ability to write to a file or the network. If desired, object can take over management of a pre-allocated buffer (with malloc or similar), free'ing it when deallocated.
The data buffer at any given time has a capacity, which is the size of its allocated memory area, in bytes, and a length, which is the length of data it is currently storing.
Method summary
+ (id)
data;
Availability: OpenStep
Returns an empty data object.
+ (id)
dataWithBytes: (const void*)bytes
length: (unsigned int)length;
Availability: OpenStep
Returns an autoreleased data object containing data copied from
bytes and with the specified
length. Invokes
-initWithBytes:length:
+ (id)
dataWithBytesNoCopy: (void*)bytes
length: (unsigned int)length;
Availability: OpenStep
+ (id)
dataWithBytesNoCopy: (void*)aBuffer
length: (unsigned int)bufferSize
freeWhenDone: (BOOL)shouldFree;
Availability: MacOS-X 10.0.0
+ (id)
dataWithContentsOfFile: (
NSString*)path;
Availability: OpenStep
+ (id)
dataWithContentsOfMappedFile: (
NSString*)path;
Availability: OpenStep
+ (id)
dataWithContentsOfURL: (
NSURL*)url;
Availability: MacOS-X 10.0.0
Retrieves the information at the specified url and returns an NSData instance encapsulating it.
+ (id)
dataWithData: (
NSData*)data;
Availability: OpenStep
Returns an autoreleased instance initialised by copying the contents of data.
- (const void*)
bytes;
Availability: OpenStep
Subclasses
should override this method.
Returns a pointer to the data encapsulated by the receiver.
- (
NSString*)
description;
Availability: OpenStep
Returns a short description of this object.
- (unsigned int)
deserializeAlignedBytesLengthAtCursor: (unsigned int*)cursor;
Availability: OpenStep
Copies data from buffer starting from
cursor.
Deprecated. Use
[-getBytes:]
and related methods instead.
- (void)
deserializeBytes: (void*)buffer
length: (unsigned int)bytes
atCursor: (unsigned int*)cursor;
Availability: OpenStep
Copies data from
buffer starting from
cursor.
Deprecated. Use
[-getBytes:]
and related methods instead.
- (void)
deserializeDataAt: (void*)data
ofObjCType: (const char*)type
atCursor: (unsigned int*)cursor
context: (id<
NSObjCTypeSerializationCallBack>)callback;
Availability: OpenStep
Description forthcoming.
- (int)
deserializeIntAtCursor: (unsigned int*)cursor;
Availability: OpenStep
Retrieve an int from this data, which is assumed to be in network (big-endian) byte order. Cursor refers to byte position.
- (int)
deserializeIntAtIndex: (unsigned int)index;
Availability: OpenStep
Retrieve an int from this data, which is assumed to be in network (big-endian) byte order. Index refers to byte position.
- (void)
deserializeInts: (int*)intBuffer
count: (unsigned int)numInts
atCursor: (unsigned int*)cursor;
Availability: OpenStep
Retrieve ints from intBuffer, which is assumed to be in network (big-endian) byte order. Count refers to number of ints, but index refers to byte position.
- (void)
deserializeInts: (int*)intBuffer
count: (unsigned int)numInts
atIndex: (unsigned int)index;
Availability: OpenStep
Retrieve ints from intBuffer, which is assumed to be in network (big-endian) byte order. Count refers to number of ints, but index refers to byte position.
- (void)
getBytes: (void*)buffer;
Availability: OpenStep
Copies the contents of the memory encapsulated by the receiver into the specified
buffer. The
buffer must be large enough to contain
-length
bytes of data... if it isn't then a crash is likely to occur.
Invokes
-getBytes:range:
with the range set to the whole of the receiver.
- (void)
getBytes: (void*)buffer
length: (unsigned int)length;
Availability: OpenStep
Copies
length bytes of data from the memory encapsulated by the receiver into the specified
buffer. The
buffer must be large enough to contain
length bytes of data... if it isn't then a crash is likely to occur.
Invokes
-getBytes:range:
with the range set to NSMakeRange(0,
length )
- (void)
getBytes: (void*)buffer
range: (
NSRange)aRange;
Availability: OpenStep
Copies data from the memory encapsulated by the receiver (in the range specified by aRange) into the specified buffer.
The buffer must be large enough to contain the data... if it isn't then a crash is likely to occur.
If aRange specifies a range which does not entirely lie within the receiver, an exception is raised.
- (id)
initWithBytes: (const void*)aBuffer
length: (unsigned int)bufferSize;
Availability: OpenStep
- (id)
initWithBytesNoCopy: (void*)aBuffer
length: (unsigned int)bufferSize;
Availability: OpenStep
- (id)
initWithBytesNoCopy: (void*)aBuffer
length: (unsigned int)bufferSize
freeWhenDone: (BOOL)shouldFree;
Availability: MacOS-X 10.0.0
This is a designated initialiser for the class.
Subclasses
should override this method.
Initialises the receiver.
The value of aBuffer is a pointer to something to be stored.
The value of bufferSize is the number of bytes to use.
The value of shouldFree specifies whether the receiver should attempt to free the memory pointer to by aBuffer when the receiver is deallocated ... ie. it says whether the receiver owns the memory. Supplying the wrong value here will lead to memory leaks or crashes.
- (id)
initWithContentsOfFile: (
NSString*)path;
Availability: OpenStep
Initialises the receiver with the contents of the specified file.
Returns the resulting object.
Returns nil
if the file does not exist or can not be read for some reason.
- (id)
initWithContentsOfMappedFile: (
NSString*)path;
Availability: OpenStep
Initialize with data pointing to contents of file at path. Bytes are only "swapped in" as needed. File should not be moved or deleted for the life of this object.
- (id)
initWithContentsOfURL: (
NSURL*)url;
Availability: MacOS-X 10.0.0
Initialize with data pointing to contents of URL, which will be retrieved immediately in a blocking manner.
- (id)
initWithData: (
NSData*)data;
Availability: OpenStep
Initializes by copying data's bytes into a new buffer.
- (BOOL)
isEqualToData: (
NSData*)other;
Availability: OpenStep
Returns a boolean value indicating if the receiver and other contain identical data (using a byte by byte comparison). Assumes that the other object is an NSData instance... may raise an exception if it isn't.
- (unsigned int)
length;
Availability: OpenStep
Subclasses
should override this method.
Returns the number of bytes of data encapsulated by the receiver.
- (
NSData*)
subdataWithRange: (
NSRange)aRange;
Availability: OpenStep
Returns an NSData instance encapsulating the memory from the receiver specified by the range aRange.
If aRange specifies a range which does not entirely lie within the receiver, an exception is raised.
- (BOOL)
writeToFile: (
NSString*)path
atomically: (BOOL)useAuxiliaryFile;
Availability: OpenStep
Writes a copy of the data encapsulated by the receiver to a file at path. If the useAuxiliaryFile flag is YES
, this writes to a temporary file and then renames that to the file at path, thus ensuring that path exists and does not contain partially written data at any point.
On success returns YES
, on failure returns NO
.
- (BOOL)
writeToURL: (
NSURL*)anURL
atomically: (BOOL)flag;
Availability: MacOS-X 10.0.0
Writes a copy of the contents of the receiver to the specified URL.
- Declared in:
- Foundation/NSData.h
Availability: OpenStep
Mutable version of
NSData
. Methods are provided for appending and replacing bytes in the buffer, which will be grown as needed.
Method summary
+ (id)
dataWithCapacity: (unsigned int)numBytes;
Availability: OpenStep
New instance with buffer of given numBytes with length of valid data set to zero. Note that capacity will be automatically increased as necessary.
+ (id)
dataWithLength: (unsigned int)length;
Availability: OpenStep
New instance with buffer of capacity and valid data size equal to given length in bytes. The buffer contents are set to zero. The length of valid data is set to zero. Note that buffer will be automatically increased as necessary.
- (void)
appendBytes: (const void*)aBuffer
length: (unsigned int)bufferSize;
Availability: OpenStep
Appends bufferSize bytes from aBuffer to data, increasing capacity if necessary.
- (void)
appendData: (
NSData*)other;
Availability: OpenStep
Copies and appends data from other to data, increasing capacity if necessary.
- (void)
increaseLengthBy: (unsigned int)extraLength;
Availability: OpenStep
Increases buffer length by given number of bytes, filling the new space with zeros.
- (id)
initWithCapacity: (unsigned int)capacity;
Availability: OpenStep
This is a designated initialiser for the class.
Initialize with buffer capable of holding size bytes. The length of valid data is initially set to zero.
- (id)
initWithLength: (unsigned int)length;
Availability: OpenStep
Initialize with buffer of capacity equal to length, and with the length of valid data set to length. Data is set to zero.
- (void*)
mutableBytes;
Availability: OpenStep
Returns a pointer to the data storage of the receiver.
Modifications to the memory pointed to by this pointer will change the contents of the object. It is important that your code should not try to modify the memory beyond the number of bytes given by the -length
method.
NB. if the object is released, or any method that changes its size or content is called, then the pointer previously returned by this method may cease to be valid.
This is a 'primitive' method... you need to implement it if you write a subclass of NSMutableData.
- (void)
replaceBytesInRange: (
NSRange)aRange
withBytes: (const void*)bytes;
Availability: OpenStep
Replaces the bytes of data in the specified range with a copy of the new bytes supplied.
If the location of the range specified lies beyond the end of the data ( [self length] < range.location
) then a range exception is raised.
Otherwise, if the range specified extends beyond the end of the data, then the size of the data is increased to accommodate the new bytes.
- (void)
replaceBytesInRange: (
NSRange)aRange
withBytes: (const void*)bytes
length: (unsigned int)length;
Availability: MacOS-X 10.0.0
Replace the content of the receiver which lies in aRange with the specified length of data from the buffer pointed to by bytes.
The size of the receiver is adjusted to allow for the change.
- (void)
resetBytesInRange: (
NSRange)aRange;
Availability: OpenStep
Set bytes in aRange to 0.
- (void)
serializeAlignedBytesLength: (unsigned int)length;
Availability: OpenStep
Does not act as the name suggests. Instead, serializes length itself as an int into buffer.
- (void)
serializeDataAt: (const void*)data
ofObjCType: (const char*)type
context: (id<
NSObjCTypeSerializationCallBack>)callback;
Availability: OpenStep
Description forthcoming.
- (void)
serializeInt: (int)value;
Availability: OpenStep
Serialize an int into this object's data buffer, swapping it to network (big-endian) byte order first.
- (void)
serializeInt: (int)value
atIndex: (unsigned int)index;
Availability: OpenStep
Serialize an int into this object's data buffer at index (replacing anything there currently), swapping it to network (big-endian) byte order first.
- (void)
serializeInts: (int*)intBuffer
count: (unsigned int)numInts;
Availability: OpenStep
Serialize one or more ints into this object's data buffer, swapping them to network (big-endian) byte order first.
- (void)
serializeInts: (int*)intBuffer
count: (unsigned int)numInts
atIndex: (unsigned int)index;
Availability: OpenStep
Serialize one or more ints into this object's data buffer at index (replacing anything there currently), swapping them to network (big-endian) byte order first.
- (void)
setData: (
NSData*)data;
Availability: OpenStep
Replaces contents of buffer with contents of data's buffer, increasing or shrinking capacity to match.
- (void)
setLength: (unsigned int)size;
Availability: OpenStep
Sets the length of the NSMutableData object. If the length is increased, the newly allocated data area is filled with zero bytes.
This is a 'primitive' method... you need to implement it if you write a subclass of NSMutableData.
- Declared in:
- Foundation/NSData.h
Availability: Base 0.0.0
Provides some shared-memory extensions to
NSData
.
Method summary
+ (id)
dataWithSharedBytes: (const void*)bytes
length: (unsigned int)length;
Availability: Base 0.0.0
New instance with given bytes in shared memory.
+ (id)
dataWithShmID: (int)anID
length: (unsigned int)length;
Availability: Base 0.0.0
New instance with given shared memory ID.
- (void)
deserializeTypeTag: (unsigned char*)tag
andCrossRef: (unsigned int*)ref
atCursor: (unsigned int*)cursor;
Availability: Base 0.0.0
Description forthcoming.
- Declared in:
- Foundation/NSData.h
Availability: Base 0.0.0
Extension methods for the NSData class- mainly conversion utilities.
Method summary
- (
NSString*)
hexadecimalRepresentation;
Availability: Base 0.0.0
Returns an NSString object containing an ASCII hexadecimal representation of the receiver. This means that the returned object will contain exactly twice as many characters as there are bytes as the receiver, as each byte in the receiver is represented by two hexadecimal digits.
The high order four bits of each byte is encoded before the low order four bits. Capital letters 'A' to 'F' are used to represent values from 10 to 15.
If you need the hexadecimal representation as raw byte data, use code like -
hexData = [[sourceData hexadecimalRepresentation] dataUsingEncoding: NSASCIIStringEncoding];
- (id)
initWithHexadecimalRepresentation: (
NSString*)string;
Availability: Base 0.0.0
Initialises the receiver with the supplied
string data which contains a hexadecimal coding of the bytes. The parsing of the
string is fairly tolerant, ignoring whitespace and permitting both upper and lower case hexadecimal digits (the
-hexadecimalRepresentation
method produces a
string using only uppercase digits with no white space).
If the
string does not contain one or more pairs of hexadecimal digits then an exception is raised.
- (
NSData*)
md5Digest;
Availability: Base 0.0.0
Creates an MD5 digest of the information stored in the receiver and returns it as an autoreleased 16 byte NSData object.
If you need to produce a digest of string information, you need to decide what character encoding is to be used and convert your string to a data object of that encoding type first using the
[NSString -dataUsingEncoding:]
method -
myDigest = [[myString dataUsingEncoding: NSUTF8StringEncoding] md5Digest];
If you need to use the digest in a human readable form, you will probably want it to be seen as 32 hexadecimal digits, and can do that using the
-hexadecimalRepresentation
method.
- (BOOL)
uudecodeInto: (
NSMutableData*)decoded
name: (
NSString**)namePtr
mode: (int*)modePtr;
Availability: Base 0.0.0
Decodes the source data from uuencoded and return the result.
Returns the encoded file name in namePtr if it is not null. Returns the encoded file mode in modePtr if it is not null.
- (BOOL)
uuencodeInto: (
NSMutableData*)encoded
name: (
NSString*)name
mode: (int)mode;
Availability: Base 0.0.0
Encode the source data to uuencoded.
Uses the supplied name as the filename in the encoded data, and says that the file mode is as specified.
If no name is supplied, uses untitled
as the name.
- Declared in:
- Foundation/NSData.h
Availability: Base 0.0.0
Provides some additional methods to
NSData
.
Method summary
- (unsigned int)
capacity;
Availability: Base 0.0.0
Returns current capacity of data buffer.
- (void)
serializeTypeTag: (unsigned char)tag;
Availability: Base 0.0.0
Description forthcoming.
- (void)
serializeTypeTag: (unsigned char)tag
andCrossRef: (unsigned int)xref;
Availability: Base 0.0.0
Description forthcoming.
- (id)
setCapacity: (unsigned int)newCapacity;
Availability: Base 0.0.0
Sets current capacity of data buffer. Unlike
-setLength:
, this will shrink the buffer if requested.
- (int)
shmID;
Availability: Base 0.0.0
Return shared memory ID, if using one, else -1.
Up