How to set the region for MKMapView in order to cover all annotations nicely:


-(void)zoomToFitMapAnnotations:(MKMapView*)mapView
{
if([mapView.annotations count] == 0)
return;

CLLocationCoordinate2D topLeftCoord;
topLeftCoord.latitude = -90;
topLeftCoord.longitude = 180;

CLLocationCoordinate2D bottomRightCoord;
bottomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;

for(MapAnnotation* annotation in mapView.annotations)
{
topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);

bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
}

MKCoordinateRegion region;
region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5;
region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;
region.span.latitudeDelta = <a href="http://www.opengroup.org/onlinepubs/009695399/functions/fabs.html">fabs</a>(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1; // Add a little extra space on the sides
region.span.longitudeDelta = <a href="http://www.opengroup.org/onlinepubs/009695399/functions/fabs.html">fabs</a>(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1; // Add a little extra space on the sides

region = [mapView regionThatFits:region];
[mapView setRegion:region animated:YES];
}

from codis.

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