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paperh18648 margl-907 margr0 margt0 margb0 fi0 ri0 ql sb0 f1 fs24 Copyright f3 'e3f1 1994 by NeXT Computer, Inc. All Rights Reserved.
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fs36 NSData
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fs28 f0 b fs24 Inherits From:tab b0 fs28 f1 NSObject
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fs28 s6 f0 b fs24 Conforms To:tab b0 fs28 f1 NSCoding, NSCopying, NSMutableCopying
fi0 NSObject (NSObject)
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fs28 s7 fi-2771 f0 b fs24 Declared In:tab b0 fs28 f1 Foundation/NSData.h
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fs28 Class Description
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fs28 The NSData class declares the programmatic interface to objects that contain data in the form of bytes. NSData objects hold a static collection of bytes; NSData'27s subclass, NSMutableData, defines objects that hold modifiable data. These two classes provide an object-oriented approach to memory allocation, a facility that in procedural programming is accessed through functions like b malloc()b0 . Furthermore, these classes take advantage of operating system primitives when allocating large blocks of memory.
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fs28 NSData'27s two primitive methods'd0b bytesb0 and b lengthb0 'd0provide the basis for all the other methods in its interface. The b bytesb0 method returns a pointer to the bytes contained in the data object. b length b0 returns the number of bytes contained in the data object.
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fs28 NSData and NSMutableData objects are commonly used to hold the contents of a file. The methods b dataWithContentsOfFile:b0 and b dataWithContentsOfMappedFile:b0 return objects that represent a file'27s contents. The b writeToFile:atomically:b0 method enables you to write the contents of a data object to a file.
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fs28 NSData provides access methods for copying bytes from a data object into a buffer. Use b getBytes:b0 to copy the entire contents of the object or b getBytes:length:b0 to copy a subset, starting with the first byte. b getBytes:range:b0 copies a range of bytes from a starting point within the bytes themselves. You can also return a data object that contains a subset of the bytes in another data object by using the b subdataWithRange:b0 method. Or, you can use the b descriptionb0 method to return an NSString representation of the bytes in a data object.
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fs28 For determining if two data objects are equal, NSData provides theb isEqualToData:b0 method, which does a byte-for-byte comparison.
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fs28 Allocating and Initializing an NSData Object
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fs28 fi-6552 + (id)b allocWithZone:b0 (NSZone *)i zonei0 tab Creates and returns an uninitialized object from i zonei0 .
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fs28 fi-6552 + (id)b datab0 tab Creates and returns an empty object. This method is declared primarily for mutable subclasses of NSData.
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fs28 fi-6552 + (id)b dataWithBytes:b0 (const void *)i bytesi0 tab Creates and returns an object containingi lengthi0 bytes
s9 li7030 fi-6553 fi-5796 b length:b0 (unsigned int)i lengthi0 tab tab of data copied from the buffer i bytesi0 .
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fs28 fi-6552 + (id)b dataWithBytesNoCopy:b0 (void *)i bytesi0 tab Creates and returns an object containing i lengthi0 bytes
s9 li7030 fi-6553 fi-5796 b length:b0 (unsigned int)i lengthi0 tab tab from the buffer i bytesi0 .
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fs28 fi-6552 + (id)b dataWithContentsOfFile:b0 (NSString *)i pathi0 tab Creates and returns an object by reading data from the file specified by i pathi0 .
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fs28 fi-6552 + (id)b dataWithContentsOfMappedFile:b0 (NSString *)i path
s9 li7030 fi-6553 fi-5796 i0 tab Creates and returns an object whose contents come from the mapped file i pathi0 , assuming mapped files are available on the underlying operating system. If mapped files are not available, this method is identical to b dataWithContentsOfFile:b0 .
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fs28 fi-6552 {f3 -} (id)b initWithBytes:b0 (const void *)i bytesi0 tab Initializes a newly allocated NSData object by putting in it
s9 li7030 fi-6553 fi-5796 length:(unsigned int)i lengthi0 tab b i i0 tab b0 i lengthb b0 i0 bytes of data copied from the buffer bytes.
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fs28 fi-6552 {f3 -} (id)b initWithBytesNoCopy:b0 (void *)i bytesi0 tab Initializes a newly allocated NSData object by putting in it
s9 li7030 fi-6553 fi-5796 length:(unsigned int)i lengthi0 tab b i tab b0 lengthb b0 i0 bytes of data from the buffer bytes.
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fs28 fi-6552 {f3 -} (id)b initWithContentsOfFile:b0 (NSString *)i pathi0 tab Initializes a newly allocated NSData object by reading into it the data from the file specified byb b0 i pathb i0 .
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fs28 fi-6552 {f3 -} (id)b initWithContentsOfMappedFile:b0 (NSString *)i path
s9 li7030 fi-6553 fi-5796 i0 tab Initializes a newly allocated NSData object to contain the data residing in the mapped fileb b0 i pathi0 , assuming mapped files are available on the underlying operating system. If mapped files are not available, this method is identical to b initWithContentsOfFile:b0 .
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fs28 fi-6552 {f3 -} (id)b initWithData:b0 (NSData *)i datai0 tab Initializes a newly allocated NSData object by placing in it the contents of another NSData object,b b0 i datai0 .
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fs28 Accessing Data
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fs28 fi-6552 {f3 -} (const void *)b bytesb0 tab Returns a pointer to the object'27s contents. This method returns read-only access to the data.
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fs28 fi-6552 {f3 -} (NSString *)b descriptionb0 tab Returns an NSString object that contains a hexadecimal representation of the the receiver'27s contents.
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fs28 fi-6552 {f3 -} (void)b getBytes:b0 (void *)i bufferi0 tab Copies the receiver'27s contents intob b0 i bufferb i0 .
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fs28 fi-6552 {f3 -} (void)b getBytes:b0 (void *)i bufferi0 tab Copies length bytes of the receiver'27s contents intob b0 i bufferb i0 .
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fs28 fi-6552 {f3 -} (void)b getBytes:b0 (void *)i bufferi0 tab Copies intob b0 i bufferb i0 b0 the portion of the receiver'27s contents
s9 li7030 fi-6553 fi-5796 range:(NSRange)aRangetab tab withinb b0 i aRangeb i0 . b0 Raises ani i0 NSRangeExceptioni i0 ifi aRangei0 is not within the range of the receiver'27s data.
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fs28 fi-6552 {f3 -} (NSData *)b subdataWithRange:b0 (NSRange)i aRangei0 tab Returns an object containing a copy of the receiver'27s bytes that fall within the limits specified by i aRangei0 . Raises ani i0 NSRangeExceptioni i0 ifi aRangei0 is not within the range of the receiver'27s data.
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fs28 Querying a Data Object
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fs28 fi-6552 {f3 -} (BOOL)b isEqualToData:b0 (NSData *)i otheri0 tab Compares the receiving object to other. If the contents ofb b0 i otheri0 are equal to the contents of the receiver, this method returns YES. If not, it returns NO.
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fs28 fi-6552 {f3 -} (unsigned int)b lengthb0 tab Returns the number of bytes contained in the receiver.
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fs28 Storing Data
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fs28 fi-6552 {f3 -} (BOOL)b writeToFile:b0 (NSString *)i pathi0 tab Writes the bytes in the receiving object to the file specified
s9 li7030 fi-6553 fi-5796 b atomically:b0 (BOOL)i useAuxiliaryFilei0 tab tab by i pathi0 . Ifi useAuxiliaryFilei0 is YES, the data is written to a backup file and then, assuming no errors occur, the backup file is renamed atomically to the intended file name.
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fs28 Deserializing Data
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fs28 fi-6552 {f3 -} (unsigned int)b deserializeAlignedBytesLengthAtCursor:b0 (unsigned int*)i cursor
s9 li7030 fi-6553 fi-5796 i0 tab Returns the length of the serialized bytes at the location referenced by i cursori0 . If the bytes have been page-aligned, it also obtains the relevant 'aahole'ba information and adjusts the cursor. An invocation of this method must have a corresponding b serializeAlignedBytesLength:b0 invocation.
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fs28 fi-6552 {f3 -} (void)b deserializeBytes:b0 (void *)i bufferi0 tab Deserializes i bytesi0 number of bytes in the buffer pointed
s9 li7030 fi-6553 fi-5796 b length:b0 (unsigned int)i bytesi0 tab tab at by i bufferi0 , places them internally starting at i cursori0 ,
b atCursor:b0 (unsigned int*)i cursori0 tab tab and advances the cursor.
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fs28 fi-6552 {f3 -} (void)b deserializeDataAt:b0 (void *)i datai0 tab Deserializes the data pointed at by i cursori0 , interpreting it
s9 li7030 fi-6553 fi-5796 b ofObjCType:b0 (const char *)i typei0 tab tab by the Objective C type specifier i typei0 and writing it
b atCursor:b0 (unsigned int*)i cursori0 tab tab to the memory location referenced by i datai0 . If the data
b context:b0 (id <NSObjCTypeSerializationCallBack>)tab tab element is an object other than an instance of
i callback i0 tab NSDictionary, NSArray, NSString, or NSData, a callback from object i callbacki0 can provide further definition of the object. All Objective C types are currently supported except b unionb0 and b void *b0 . Pointers refer to a single item.
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fs28 fi-6552 {f3 -} (int)b deserializeIntAtCursor:b0 (unsigned int*)i cursori0 tab Deserializes and returns the integer encoded at i cursori0 . Also advances the cursor.
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fs28 fi-6552 {f3 -} (int)b deserializeIntAtIndex:b0 (unsigned int)i indexi0 tab Deserializes and returns the integer encoded at offset i indexi0 . Does not advance the cursor.
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fs28 fi-6552 {f3 -} (void)b deserializeInts:b0 (int *)i intBufferi0 tab Deserializes i numIntsi0 integers encoded at the location
s9 li7030 fi-6553 fi-5796 b count:b0 (unsigned int)i numIntsi0 tab tab referenced by i cursori0 and puts them in the buffer
b atCursor:b0 (unsigned int*)i cursori0 tab tab i intBufferi0 . Also advances the cursor.
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fs28 fi-6552 {f3 -} (void)b deserializeInts:b0 (int *)i intBufferi0 tab Deserializes i numIntsi0 integers encoded at offset i index
s9 li7030 fi-6553 fi-5796 i0 b count:b0 (unsigned int)i numIntsi0 tab tab and puts them in the buffer i intBufferi0 . Does not advance
b atIndex:b0 (unsigned int)i indexi0 tab tab the cursor.
}These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.