annotation images changing after reuse - annotations

Question

My problem is similar to this one
Displaying custom multiple pins shows wrong pins for locations
but slightly different and I'm working in Swift. Even after converting, I couldn't get the solution to my problem.
I have annotations with a different image for each. The images are numbered pointers. The details of each annotation comes from a plist. The titles are such as "1 car park", "2 mill" etc. I take the part before the space to get the number which corresponds to a png image.
On loading, all annotations have the correct image. If I pan off the area and come back the images can swap with each other. It seems to be a problem of reusing, but I can't see the solution. getMapAnnotations() is called in viewdidload.
func getMapAnnotations() -> [Stands] {
var annotations:Array = [Stands]()
print("ANNOTATIONS")
//load plist file
var stands: NSArray?
if let path = Bundle.main.path(forResource: "stands", ofType: "plist") {
stands = NSArray(contentsOfFile: path)
}
//iterate and create annotations
if let items = stands {
for item in items {
let lat = (item as AnyObject).value(forKey: "lat") as! Double
let long = (item as AnyObject).value(forKey: "long")as! Double
let annotation = Stands(latitude: lat, longitude: long)
let tit = (item as AnyObject).value(forKey: "title") as! String
let numb = (item as AnyObject).value(forKey: "no") as! Int
annotation.title = "\(numb) \(tit)"
annotation.no = numb
annotations.append(annotation)
}
}
return annotations
}
then the annotation view
func mapView(_ mapView: MKMapView!, viewFor annotation: MKAnnotation!) -> MKAnnotationView! {
let identifier = "Stand"
var imageI: String?
var imageAn: String?
imageI = annotation.title!
if annotation.isKind(of: Stands.self) {
print("ANNOTATION \(imageI!)")
if let range = imageI?.components(separatedBy: " ") {
var imageII = range[0]
imageAn = "\(imageII).png"
print (imageAn!)
}
var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier)
if annotationView == nil {
annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: identifier)
//
annotationView?.image = UIImage(named: imageAn! )
annotationView?.canShowCallout = true
annotationView?.layer.zPosition = -1
let btn = UIButton(type: .detailDisclosure)
annotationView?.rightCalloutAccessoryView = btn
} else {
annotationView!.annotation = annotation
}
return annotationView
}
return nil
}

Answer 1

I seem to have found the solution , more by trial and error than knowing what I'm doing.
I added
annotationView?.image = UIImage(named: imageAn! )
to make
}else{
annotationView?.image = UIImage(named: imageAn! )
annotationView.annotation = annotation
}
if I understand correctly , annotation is the information of the coordinates, title and subtitle with no information about display.
AnnotationView sets up how the annotation will be displayed. With a pin or custom image.
If AnnotationView is nill the annotation views are created correctly. If the annotations go out of view and come back, AnnotationView is not nil so the system takes a view at random to display it.
Adding
annotationView?.image = UIImage(named: imageAn! )
forces the correct image to be displayed.
I'm sure someone will correct me if this schema isn't correct.