Semantic Zoom in iOS

How would one go about creating a semantic zoom type interface in iOS4? By semantic zoom I mean that as the user zooms in on an object it reveals more and more details, and vice versa when z开发者_如何学编程ooming out.

Any tips appreciated, thanks!

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I think there was a WWDC session video on this and it used a UIScrollView and tiling. When the user zoomed a more detailed image was shown on the tiles. Take a look at the session videos (link is in the developer center and you will need a developer account).

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The "PhotoScroller" sample code provided by Apple has a tiled zoom technique that works very well. I have reused it across multiple apps. It relies on CATiledLayer. Download the sample code and you should have what you need.