MKMapView setRegion “snaps” to predefined zoom levels?

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Yes, it snaps to discrete levels. I’ve done quite a bit of experimentation, and it seems to like multiples of 2.68220906e-6 degrees of longitude per pixel.

So if your map fills the whole width of the screen, the first level spans .0008583 degrees, then the next level up you can get is twice that, .001717, and then the next one is twice that, .003433, and so on. I’m not sure why they chose to normalize by longitude, it means that fixes zoom levels vary depending on what part of the world you are looking at.

I’ve also spent a lot of time trying to understand the significance of that number .68220906e-6 degrees. It comes out to about 30cm at the equator, which kind of makes sense since the high resolution photos used by Google Maps have a 30cm resolution, but I would have expected them to use latitude instead of longitude to establish the zoom levels. That way, at maximum zoom, you always the native resolution of the satellite images, but who knows, they probably have some smart-people reason for making it work like that.

In my application I need to display a certain range of latitude. I’m gonna work on some code to try to zoom the map as close as possible to that. If anyone is interested, contact me.

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