Refactor

Map

// MARK: - IBActions
    
    @IBAction func zoomInButtonTaped(_ sender: UIButton) {
        Zoom.In.at(self.mapView)
    }
    
    @IBAction func zoomOutButtonTaped(_ sender: UIButton) {
        Zoom.Out.at(self.mapView)
    }
    
fileprivate enum Zoom: Double  {
    case In = 0.5
    case Out = 2
    
    func at(_ mapView:MKMapView) {
        let span = mapView.region.span
        let degrees = [span.longitudeDelta,span.longitudeDelta].map { $0 * rawValue }
        let newSpan = MKCoordinateSpan(latitudeDelta: minDegree(degrees[0]),
                                       longitudeDelta: minDegree(degrees[1]))
        mapView.setRegion(MKCoordinateRegion(center: mapView.region.center, span: newSpan), animated: true)
    }
    
    //To drop hight values
    fileprivate func minDegree(_ value:CLLocationDegrees ) -> CLLocationDegrees {
        return min(value , Constants.Map.MaxSpan)
    }
}