MKMapView Zoom and Region

I'm familiar with using Google Maps Javascript API. Recently I started using MapKit framework for an iphone project, but I'm having a hard time to figure out zooming and setting a region on map.

In Google Maps API I used to use integer zoom levels like 8, 9, 10 along with straightforward function setZoom(). The only equivalent method I can see in the MapKit framework is setRegion:animated. As I understand, I need to set a region's span's latitude and longitude "delta" values to specify zoom level. But I really don't have an idea what these values represent(I read the documentation).

When I use a MKMapView delegate and trace the span values in regionDidChange delegate method results don't seem to correlate each other. It's ok when I zoom out and see the span delta values are increasing as specified in documentation. But suddenly I drag the map without zooming and delta values become 0.0.

Can somebody please explain what is the reference point to these span and delta? Or is there any algorithm to convert an integer zoom level(like 9) to these delta values?

As a bonus question is there any way to specify a minimum-maximum zoom level on a MKMapView :)

Thanks

Edit Report

The span is in degrees of latitude and longitude. There is a method for constructing MKCoordinateRegion structs that takes distance, instead. It may be that you are using MKCoordinateRegionMakeWithDistance to specify the span, and then when you check it in regionDidChange, you're seeing at the lat/long span, which is how it is stored in an MKCoordinateRegion struct.

As far as I know, the integer zoom levels are not available or useful at all when working with MKMapKit. I personally prefer using the span figures, its more flexible.

You cannot specify max and min zoom, and I don't know of a way to hack it in. MKMapKit is actually pretty weak right now, I'm pretty disappointed by the lack of features.

answered 2009-07-22T18:09:46.623

MKMapView Zoom and Region

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