How to zoom in double in MapKit

Issue #183

func zoomInDouble(coordinate: CLLocationCoordinate2D) {
    let region = mapView.region
    let zoomInRegion = MKCoordinateRegion(
        center: coordinate,
        span: MKCoordinateSpan(
            latitudeDelta: region.span.latitudeDelta * 0.5,
            longitudeDelta: region.span.longitudeDelta * 0.5
        )
    )
    
    mapView.setRegion(zoomInRegion, animated: true)
}