iPhone Retina Graphics

I have a question RE Retina display graphics (and potentially iPad 2 graphics if the rumours of double resolution displays are to be believed).

Is there any advantage to having two graphics: Graphic.png 480x320 and Graphic@2.png 960x640

and letting the iPhone use the @2 version for retina displays rather than just having Graphic.png at the higher res and letting iPhones 开发者_开发知识库with normal displays squash it?

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Yes. If you didn't use two separate graphics (normal and "@2x"), any device without the retina display would have to store its graphics using four times as much memory. It's a simple matter of storing an insignificant amount of compressed images (PNGs) so you don't have to kill legacy devices' memory.

Not only that, but performance will drop from having to handle such large images on devices that are generally slower.

Finally, the result of scaling huge images is usually really ugly, because UIKit uses the nearest-neighbor algorithm when scaling.