Businessweek Interviews Federighi and Ive
Ive: The parallax is a nice example. One of the things that we were interested in doing is, despite people talked about this being “flat,” is that it’s very, very deep. It’s constructed and architected visually and from an informational point of view as a very deep UI, but we didn’t want to rely on shadows or how big your highlights could get. Where do you go? I mean, there is only so long you can make your shadows.
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Federighi: If that became laggy, separated in time, your own mental model for what you were doing would be broken, and suddenly we’d have a much more complex interaction problem to solve for the user. But if we could solve all the problems of the latency and the touch screen, the hardware problem, the speed of the graphics to move it, then suddenly we didn’t have to teach you because we created something that you could process intuitively. We tend to think how can we make it so effective that there is nothing to teach.
On my iPhone 4S, the animation is smooth, but it makes the OS feel slow.