将Hex的字符串转换为文本的NSString？

NSString *hexString = @"48656c6c6f20576f726c64"; // Hex字符串
NSMutableData *data = [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [hexString length]/2; i++) {
    byte_chars[0] = [hexString characterAtIndex:i*2];
    byte_chars[1] = [hexString characterAtIndex:i*2+1];
    whole_byte = strtol(byte_chars, NULL, 16);
    [data appendBytes:&whole_byte length:1];
}

NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];