I would imagine that it is cast and then machined. At least, I thought all these Apple products were being machined...
BTW, on a side note. I visited a couple of faucet factories in GD recently. Basically the same process. Brass casting the basic form, machining to form flat surfaces for seals, tapping the threads for assembly, polishing the exterior for a smooth finish. It's not that complicated (at least when you are chroming brass).
"L'homme n'est rien. L'œuvre c'est tout." Gustave Flaubert