Two simple Objective-C classes that make it crazy easy to read data from sequential binary files.

BinaryDataScanner.h

//
//  BinaryDataScanner.m
//
//  Copyright 2009 Dave Peck <davepeck [at] davepeck [dot] org>. All rights reserved.
//  http://davepeck.org/
//
//  This class makes it quite a bit easier to read sequential binary files in Objective-C.
//
//  This code is released under the BSD license. If you use it in your product, please
//  let me know and, if possible, please put me in your credits.
//

#import <UIKit/UIKit.h>

@interface BinaryDataScanner : NSObject {
	BOOL littleEndian;
	NSStringEncoding encoding;
	NSData *data;
	const uint8_t *current;
	NSUInteger scanRemain;
}

+(id)binaryDataScannerWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding;

-(NSUInteger) remainingBytes;
-(const uint8_t *) currentPointer;

-(void) skipBytes:(NSUInteger)count;
-(uint8_t) readByte;
-(uint16_t) readWord;
-(uint32_t) readDoubleWord;
-(NSString*) readNullTerminatedString;
-(NSString*) readNullTerminatedStringWithEncoding:(NSStringEncoding)overrideEncoding;
-(NSString*) readStringUntilDelimiter:(uint8_t)delim;
-(NSString*) readStringUntilDelimiter:(uint8_t)delim encoding:(NSStringEncoding)overrideEncoding;
-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull;
-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull encoding:(NSStringEncoding)overrideEncoding;
-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count;
-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count encoding:(NSStringEncoding)overrideEncoding;

@end

BinaryDataScanner.m

//
//  BinaryDataScanner.m
//
//  Copyright 2009 Dave Peck <davepeck [at] davepeck [dot] org>. All rights reserved.
//  http://davepeck.org/
//
//  This class makes it quite a bit easier to read sequential binary files in Objective-C.
//
//  This code is released under the BSD license. If you use it in your product, please
//  let me know and, if possible, please put me in your credits.
//


#import "BinaryDataScanner.h"

// NS byte order stuff is not useful here -- CF byte order ensures we're always dealing
// with the right size on either 32 or 64 bit platforms.
#import <CoreFoundation/CFByteOrder.h>


@interface BinaryDataScanner (Private)

-(id)initWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding;
-(void)dealloc;
-(NSException *)buildScanException;
-(void)moveBy:(NSUInteger)count;

@end


@implementation BinaryDataScanner (Private)

-(id)initWithData:(NSData*)initData littleEndian:(BOOL)isLittleEndian defaultEncoding:(NSStringEncoding)theDefaultEncoding
{
	self = [super init];
	if (self != nil)
	{
		data = [initData retain];		
		littleEndian = isLittleEndian;
		encoding = theDefaultEncoding;
		current = (const uint8_t *) [data bytes];
		scanRemain = [data length];
	}
	return self;
}

-(void)dealloc
{
	[data release];
	data = nil;
	[super dealloc];
}

-(void)moveBy:(NSUInteger)count
{
	if (scanRemain < count)
	{
		@throw [self buildScanException];
	}
		
	scanRemain -= count;
	current += count;
}

-(NSException *)buildScanException
{
	return [NSException exceptionWithName:@"OrangeDataScanException" reason:@"Failure scanning desired information from the bytes." userInfo:nil];	
}

@end


@implementation BinaryDataScanner

+(id)binaryDataScannerWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding
{
	return [[[BinaryDataScanner alloc] initWithData:data littleEndian:littleEndian defaultEncoding:defaultEncoding] autorelease];
}

-(NSUInteger) remainingBytes
{
	return scanRemain;
}

-(const uint8_t *) currentPointer
{
	return current;
}

-(void) skipBytes:(NSUInteger)count
{
	[self moveBy:count];
}

-(uint8_t) readByte
{
	const uint8_t *old = current;
	[self moveBy:1];
	return old[0];
}

-(uint16_t) readWord
{
	const uint16_t *word = (const uint16_t *) current;
	[self moveBy:sizeof(uint16_t)];
	if (littleEndian)
	{
		return CFSwapInt16LittleToHost(*word);
	}
	else
	{
		return CFSwapInt16BigToHost(*word);
	}
}

-(uint32_t) readDoubleWord
{
	const uint32_t *dword = (const uint32_t *) current;
	[self moveBy:sizeof(uint32_t)];
	if (littleEndian)
	{
		return CFSwapInt32LittleToHost(*dword);
	}
	else
	{
		return CFSwapInt32BigToHost(*dword);
	}
}

-(NSString*) readNullTerminatedString
{
	return [self readNullTerminatedStringWithEncoding:encoding];
}

-(NSString*) readNullTerminatedStringWithEncoding:(NSStringEncoding)overrideEncoding
{
	return [self readStringUntilDelimiter:0 encoding:overrideEncoding];
}

-(NSString*) readStringUntilDelimiter:(uint8_t)delim
{
	return [self readStringUntilDelimiter:delim encoding:encoding];
}

-(NSString*) readStringUntilDelimiter:(uint8_t)delim encoding:(NSStringEncoding)overrideEncoding
{
	const uint8_t *start = current;
	NSUInteger stringLength = 0;
	
	while (scanRemain > 0 && *current != delim)
	{		
		scanRemain -= 1;
		current += 1;
		stringLength += 1;
	}
	
	if (scanRemain < 1 || *current != delim)
	{
		@throw [self buildScanException];
	}
	
	// move over the delimiter
	[self moveBy:1];
	
	NSString *result = [[NSString alloc] initWithBytes:(const void*)start length:stringLength encoding:overrideEncoding];	
	return [result autorelease];
}

-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull
{
	return [self readStringOfLength:count handleNullTerminatorAfter:handleNull encoding:encoding];
}

-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull encoding:(NSStringEncoding)overrideEncoding
{
	const uint8_t *start = current;
	[self moveBy:count];

	if (handleNull)
	{
		const uint8_t *nullTerminator = current;
		[self moveBy:1];
		if (*nullTerminator != 0) 
		{
			@throw [self buildScanException];
		}
	}
	
	NSString *result = [[NSString alloc] initWithBytes:(const void*)start length:count encoding:overrideEncoding];
	return [result autorelease];
}

-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count
{
	return [self readArrayOfNullTerminatedStrings:count encoding:encoding];
}

-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count encoding:(NSStringEncoding)overrideEncoding
{
	NSMutableArray *array = [NSMutableArray arrayWithCapacity:count];
	
	for (NSUInteger i = 0; i < count; i++)
	{
		[array addObject:[self readNullTerminatedStringWithEncoding:overrideEncoding]];
	}
	
	return [array autorelease];
}

@end

Hi, I"m a newb to Objective C, and am writing for Mac. It seems that UIKit is for iOS...

Yeah that UIKit import probably doesn't need to be there.

Hi, can you please tell me on what version of the bsd license is the code released?
Thank you.