I have some annotations presented on a map (somepoints) the map zooms in or out to fit all points - see working code below.
MKPolygon *poly = [MKPolygon polygonWithPoints:somepoints count:i];
[self.mapView setRegion:MKCoordinateRegionForMapRect([poly boundingMapRect]) animated:NO];
Q: I would like to expand this poly just slightly to have some margins, how can I enlarge this Region?
You can increase the span of the region in order to add some margin:
MKCoordinateRegion region = MKCoordinateRegionForMapRect([poly boundingMapRect]);
region.span.latitudeDelta *= 1.2; // Increase span by 20% to add some margin
region.span.longitudeDelta *= 1.2;
[self.mapView setRegion:region animated:YES];