Get the MKCoordinateRegion that encompasses a set of MKAnnotations

gistfile1.m

// returns a MKCoordinateRegion that encompasses an array of MKAnnotations

- (MKCoordinateRegion)regionForAnnotations:(NSArray *)annotations {
    
    CLLocationDegrees minLat = 90.0;
    CLLocationDegrees maxLat = -90.0;
    CLLocationDegrees minLon = 180.0;
    CLLocationDegrees maxLon = -180.0;
    
    for (id <MKAnnotation> annotation in annotations) {
        if (annotation.coordinate.latitude < minLat) {
            minLat = annotation.coordinate.latitude;
        }		
        if (annotation.coordinate.longitude < minLon) {
            minLon = annotation.coordinate.longitude;
        }		
        if (annotation.coordinate.latitude > maxLat) {
            maxLat = annotation.coordinate.latitude;
        }		
        if (annotation.coordinate.longitude > maxLon) {
            maxLon = annotation.coordinate.longitude;
        }
    }
    
    MKCoordinateSpan span = MKCoordinateSpanMake(maxLat - minLat, maxLon - minLon);
    
    CLLocationCoordinate2D center = CLLocationCoordinate2DMake((maxLat - span.latitudeDelta / 2), maxLon - span.longitudeDelta / 2);
    
    return MKCoordinateRegionMake(center, span);
}

No need of this anymore, From iOS 7 We can directly use this Api to set the region so all the given annotations are visible.

self.mapView.showAnnotations(annotations, animated: true)

No need of this anymore, From iOS 7 We can directly use this Api to set the region so all the given annotations are visible.

self.mapView.showAnnotations(annotations, animated: true)

That fine if you want to zoom everything to fit in the center of the map. But sometimes you want to offset it (like if you have a bottom sheet that covers half the map).

You need to be able to get a region that fits the coordinates to offset it. So this is still valid code.