Pan to new mapView Annotation Location - not zoom - mkmapview

Question

When adding an annotation to my mapView using mapView.addAnnotation, mapView.setRegion correctly animates and displays the map's center & span.
But when adding a new annotation and then calling mapView.setRegion, the view again starts from very wide, and then animates/zooms in to the new center & span.
I would like to know if there is a way to PAN from the previous region to the new region (center & span), rather than starting zoomed out, then zooming all the way back in again.
mapView.setRegion starts zoom from way out here each time:
I have defined 2 custom classes : MarkAnnotation & MarkAnnotationView
class MarkAnnotation : NSObject, MKAnnotation {
var coordinate: CLLocationCoordinate2D
var title: String?
var subtitle: String?
init(coordinate: CLLocationCoordinate2D, title: String, subtitle: String) {
self.coordinate = coordinate
self.title = title
self.subtitle = subtitle
}
}
class MarkAnnotationView: MKAnnotationView {
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)
guard let markAnnotation = self.annotation as? MarkAnnotation else { return }
image = UIImage(named: "customAnnotation")
}
}
and in my MKMapViewDelegate :
func addMarkAnnotation() {
for mark in marks {
let markName : String = mark.name
let markLat : Double = mark.lat
let markLon : Double = mark.lon
let markLL = CLLocationCoordinate2DMake(markLat, markLon)
let markAnnotation = MarkAnnotation(coordinate:markLL, title:markNumStr, subtitle: markName)
mapView.addAnnotation(markAnnotation)
}
}
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
let annotationView = MarkAnnotationView(annotation: annotation, reuseIdentifier: "MarkView")
annotationView.canShowCallout = true
return annotationView
}
func centerMapOnLocation(location:CLLocation, span:Double) {
let mapSpan = MKCoordinateSpanMake(0.2, 0.2)
let recenterRegion = MKCoordinateRegion(center: location.coordinate, span: mapSpan)
mapView.setRegion(recenterRegion, animated: true)
}
And then in the ViewController, when user presses a button, a mark is added at a specified lat/lon
func addMarkBtnPressed() {
// .... (have not shown : conversion of text fields from String to Double, adding Mark to marks array, etc ) ... All this works fine
addMarkAnnotation()
let mapCenter = CLLocation(latitude: markLat, longitude: markLon)
centerMapOnLocation(location: mapCenter, span: span)
}

Answer 1

Try the following code:
func centerMapOnLocation(location:CLLocation, span:Double) {
let mapSpan = mapView.region.span
let recenterRegion = MKCoordinateRegion(center: location.coordinate, span: mapSpan)
mapView.setRegion(recenterRegion, animated: true)
}