CocoaDev

More than once I’ve needed to read data stored in NSData objects, and the default output of -[NSData describe] is not really very human-readable. Thus, I created a small category to make traditional hex dumps from NSData objects, and an override for describe to make it the default output format. The code should be self-explanatory, and can just be dropped into any project. Enjoy! - WAHa

@implementation NSData (HexDump)

-(NSString *)hexDumpWithColumns:(int)cols { NSMutableString *str=[NSMutableString string]; unsigned int len=[self length]; const unsigned char *bytes=[self bytes]; int lines=(len+cols-1)/cols;

for(int i=0;i<lines;i++)
{
	[str appendFormat:@"%08x   ",i*cols];

	for(int j=0;j<cols;j++)
	{
		int offs=i*cols+j;
		if(offs>=len) [str appendString:@"  "];
		else [str appendFormat:@"%02x",bytes[i*cols+j]];
		if(j%4==3&&j!=cols-1) [str appendString:@" "];
	}

	[str appendString:@"   "];

	for(int j=0;j<cols;j++)
	{
		int offs=i*cols+j;
		if(offs>=len) [str appendString:@" "];
		else
		{
			int c=bytes[i*cols+j];
			if(c<0x20||(c>=0x80&&c<0xa0)) c='.';
			[str appendFormat:@"%c",c];
		}
	}

	if(i!=lines-1) [str appendString:@"\n"];
}
return str; }

-(NSString *)description { return [NSString stringWithFormat:@”<\n%@\n>”,[self hexDumpWithColumns:16]]; }

@end

The output looks pretty much like this:

00000090 416e7441 656e756d 00000000 416e6e74 AntAenum….Annt 000000a0 00000000 416e536d 00000009 54657874 ….AnSm….Text 000000b0 496e6465 786c6f6e 67000000 04000000 Indexlong……. 000000c0 0a456e67 696e6544 61746174 64746100 .EngineDatatdta. 000000d0 0048650a 0a3c3c0a 092f456e 67696e65 .He..«../Engine 000000e0 44696374 0a093c3c 0a09092f 45646974 Dict..«…/Edit

see also: http://www.red-sweater.com/blog/279/hexy-little-thing

Hah, funny how that code ends up being structured nearly the same. I guess there is just the one obvious solution to this one – WAHa