问题
It is well known that using setRegion with MkMapKit under ios5 snaps
to the next available Google zoom level, so a precise programatic setting of the map region was not possible (without special tricks, like using transformation matrix on mapView)
But for some strange reasons using setRegion or setMapRect under iOS 6.1.3 iphone4 shows the same behavior as in iOS5, although this works on ipad ios6.1.3.
iphone4 and simulator can only use regions double or half size from the prevoius one.
So there must be something that the MkMapKit forces to behave like iOS5 although having vectors. This happens on ios simulator, on ios4 device, but not on iPad with ios 6.1.3
I change the region 2 seconds after end of viewDidAppear(), so this cannot be a timing issue. The region values are precisly calculated.
I have set deployment target to ios 6.1 and am developping under Xcode 4.6, but the project was created 2 years ago under Xcode 3.
The only thing that is a bit unusual, is that my mkMapView.frame is quadratic, and bigger than the screen, equal to the diagonal (for self rotating).
How do i solve that, such that setRegion exactly uses the specified longitudinal span?
Or is this known that it does not work?
来源：https://stackoverflow.com/questions/18166176/mkmapview-setregion-under-ios6-snaps-to-grid-like-ios5-no-precise-setregion-pos