Adding some private instance variables for foreground, midground and hud node
Adding some private instance variables for foreground, midground and hud node

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