It probably is just a Gaussian blur applied to a depth map. The halo artifacts on the colored spots are a bit bad; they could have chosen better examples. Then

It probably is just a Gaussian blur applied to a depth map. The halo artifacts on the colored spots are a bit bad; they could have chosen better examples. Then again, it's not bad for what essentially is a research prototype. Since it's done in software, Apple could use a more uniform circle kernel instead of a Gaussian kernel to do a more authentic bokeh style.