MapTableViewController-2.swift

func addPointAndCircleToMapView( lat: Double, lon: Double, radius: Int, content: String) {
    let newPin = MKPointAnnotation()
    let coordinate = CLLocationCoordinate2D(latitude: lat,longitude: lon)
    newPin.coordinate = coordinate
    newPin.title = content
    let circle = MKCircle(center: coordinate, radius: CLLocationDistance(radius))
    mapView.add(circle)
    mapView.addAnnotation(newPin)
}

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    guard overlay is MKCircle else { return MKOverlayRenderer() }
    let circle = MKCircleRenderer(overlay: overlay)
    circle.strokeColor = UIColor.red
    circle.fillColor = UIColor(red: 255, green: 0, blue: 0, alpha: 0.1)
    circle.lineWidth = 1
    return circle
}