That iPad flows together with all of the matter around it. You can't see the gas particles in the air interacting with the chemical matrix of the iPad, but the only thing that changes between the iPad and the air is the conformation of the matter. Conformation of matter changes in gas, too, from pocket to pocket; but we do not consider different pockets of air to be different objects. Even within the iPad, conformation of matter is not constant. So it comes down to a question of how much of a change in the conformation of matter is necessary to distinguish an object from another? And this is where the lines we could draw become arbitrary.