packing some data

pack.m

- (NSData *)build
{
    uint32_t type = _type;        // 0
    uint32_t command = _command;  // 3
    NSString *data = _data;       // @""
    unsigned char byte = 0x00;    // 0
    
    unsigned long size = sizeof(command) + sizeof(type) + data.length + sizeof(byte);  // 9
    unsigned long totalSize = sizeof(uint32_t) + size;                                 // 10 (including size uint32)
    unsigned char bytes[totalSize];
    
    NSLog(@"Stats: %lu, %lu", size, totalSize);  // Stats: 9, 13
    
    uint32_t b;
    unsigned char *p;
    
    // Size
    b = htonl(size);
//    memcpy(bytes, &b, sizeof(b));
    p = (unsigned char *)&b;
    bytes[0] = p[0];
    bytes[1] = p[1];
    bytes[2] = p[2];
    bytes[3] = p[3];
    
    // Command
    b = htonl(command);
    memcpy(bytes + 4, &b, sizeof(b));
    
    // Type
    b = htonl(type);
    memcpy(bytes + 8, &b, sizeof(b));
    
    // Data
    const char *dataBytes = [data UTF8String];
    
    for(UInt32 i = 0; i < data.length; ++i)
    {
        bytes[i + 12] = dataBytes[i];
    }
    
    bytes[totalSize - 1] = byte;
    
    NSData *d = [NSData dataWithBytes:&bytes length:totalSize];
    
    NSMutableString *str = [NSMutableString new];
    
    for(UInt32 i = 0; i < totalSize; ++i)
    {
        if(i < 12 || i == totalSize - 1)
        {
            [str appendFormat:@"%i", bytes[i]];
        }else
        {
            [str appendFormat:@"%c", bytes[i]];
        }
    }
    
    NSLog(@"Sending: %@", str);  // Sending: 0009000300000
    
    return d;
}