1 year old and hitting....

So my 1 year old has gotten to where she starts to hit. I've patted her hands and tell her "no no" but she just hits back. She will also slap you in the face. Other than that she's a sweet baby. She will give you lovings and laugh at you but if you dont give her what she wants (it happens mostly with food. Like if I am eating and dont share she will start hitting) what can I do to make her stop hitting?