Positioning MKMapView to show multiple annotations at once

The link posted by Jim is now dead, but i was able to find the code (which I had bookmarked somewhere). Hope this helps.

- (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(id<MKAnnotation> 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;          // Add a little extra space on the sides    region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1;    region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1;     region = [mapView regionThatFits:region];     [mapView setRegion:region animated:YES]; }

Why so complicated?

MKCoordinateRegion coordinateRegionForCoordinates(CLLocationCoordinate2D *coords, NSUInteger coordCount) {    MKMapRect r = MKMapRectNull;    for (NSUInteger i=0; i < coordCount; ++i) {        MKMapPoint p = MKMapPointForCoordinate(coords[i]);        r = MKMapRectUnion(r, MKMapRectMake(p.x, p.y, 0, 0));    }    return MKCoordinateRegionForMapRect(r);}

As of iOS7 you can use showAnnotations:animated:

[mapView showAnnotations:annotations animated:YES];