NSData to HexString and HexString to NSData

Hi everyone,
Here, I've put two different methods for the conversion of "HEXString" to "NSData" and "NSData" to "HEXString".  you may get help from these two. Please ask if you have any query.


- (NSData *)dataFromHexString:(NSString *)string
{  
    NSMutableData *stringData = [[[NSMutableData alloc] init] autorelease];
    unsigned char whole_byte;
    char byte_chars[3] = {'\0','\0','\0'};
    int i;
    for (i=0; i < [string length] / 2; i++) {
        byte_chars[0] = [string characterAtIndex:i*2];
        byte_chars[1] = [string characterAtIndex:i*2+1];
        whole_byte = strtol(byte_chars, NULL, 16);
        [stringData appendBytes:&whole_byte length:1];
    }
    return stringData;
}

- (NSString*)hexStringFromData:(NSData *)data
{
    unichar* hexChars = (unichar*)malloc(sizeof(unichar) * (data.length*2));
    unsigned char* bytes = (unsigned char*)data.bytes;
    for (NSUInteger i = 0; i < data.length; i++) {
        unichar c = bytes[i] / 16;
        if (c < 10) c += '0';
        else c += 'a' - 10;
        hexChars[i*2] = c;
        c = bytes[i] % 16;
        if (c < 10) c += '0';
        else c += 'a' - 10;
        hexChars[i*2+1] = c;
    }
    NSString* retVal = [[NSString alloc] initWithCharactersNoCopy:hexChars
                                                           length:data.length*2
                                                     freeWhenDone:YES];
    return [retVal autorelease];
}


If any one has query then share it over here.

Thanks and Regards,
Nilesh Prajapati