Update annotations loaded with http - swift

Question

I am loading some GeoData from my server and want to display them throw annotations:
Alamofire.request("http://localhost:1234/app/data").responseJSON { response in
switch response.result {
case .success(let value):
let json = JSON(value)
var annotations = [Station]()
for (key, subJson):(String, JSON) in json {
let lat: CLLocationDegrees = subJson["latitude"].double! as CLLocationDegrees
let long: CLLocationDegrees = subJson["longtitude"].double! as CLLocationDegrees
self.annotations += [Station(name: "test", lat: lat, long: long)]
}
DispatchQueue.main.async {
let allAnnotations = self.mapView.annotations
self.mapView.removeAnnotations(allAnnotations)
self.mapView.addAnnotations(annotations)
}
case .failure(let error):
print(error)
}
}
and my Station class:
class Station: NSObject, MKAnnotation {
var identifier = "test"
var title: String?
var coordinate: CLLocationCoordinate2D
init(name:String, lat:CLLocationDegrees, long:CLLocationDegrees) {
title = name
coordinate = CLLocationCoordinate2DMake(lat, long)
}
}
So what I did, is basically:
Load data from remote service and display these data as annotations on MKMapView.
But: somehow these annotations are not loaded on the map, even i first "remove" and next "add" them.
Any suggestions?

Answer 1

You're adding your Station instances to some self.annotations property, not your local variable, annotations. Thus, annotations local var is still just that empty array.
Obviously, you can fix that by referencing annotations rather than self.annotations:
var annotations = [Station]()
for (key, subJson): (String, JSON) in json {
let lat = ...
let long = ...
annotations += [Station(name: "test", lat: lat, long: long)] // not `self.annotations`
}
Or you can use map, avoiding this potential confusion altogether:
let annotations = json.map { key, subJson -> Station in
Station(name: "test", lat: subJson["latitude"].double!, long: subJson["longitude"].double!)
}