Added the categoryBitMask to AlienCategory
Added the categoryBitMask to AlienCategory

hanhailong/practice-swift,nguyenantinhbk77/practice-swift,domenicosolazzo/practice-swift,domenicosolazzo/practice-swift,nguyenantinhbk77/practice-swift,nguyenantinhbk77/practice-swift,hanhailong/practice-swift,nguyenantinhbk77/practice-swift,hanhailong/practice-swift,domenicosolazzo/practice-swift,hanhailong/practice-swift,domenicosolazzo/practice-swift