How to update Google Maps marker position in swift/iOS - ios

Question

I would like to have multiple markers and update their position, based on new data from server. This is how I show marker on map (basic stuff):
func showMarkerOnMap() {
mapView.clear() //<- That's GMSMapView
for all in dataFromServer {
let lat5 = all.latitude
let lon5 = all.longitude
let position = CLLocationCoordinate2DMake(lat5, lon5)
let marker = GMSMarker(position: position)
marker.flat = true
marker.map = self.mapView
}
}
This is how I get dataFromServer using Alamofire:
var dataFromServer = [dataClass]()
func getCoordinatesFromServer(){
//Here goes headers and authentication data
Alamofire.request(.GET, URL, headers: headers).authenticate(user: oranges, password: appels).responseJSON { response in
switch response.result {
case .Success:
//Remove existing dataFromServer
self.dataFromServer.removeAll()
if let value = response.result.value {
let json = JSON(value)
for result in json.arrayValue {
let lat = result["latitude"].doubleValue
let lon = result["longitude"].doubleValue
let zip = dataClass(latitude: lat, longitude: lon)
//The next part is for checking that coordinates do not overlap
if self.dataFromServer.count < 1 {
self.dataFromServer.append(zip)
} else {
for all in self.dataFromServer {
guard all.latitude != lat else {
return
}
self.trblInfo1.append(zip)
}
}
}
//This should update existing markers?
self.showMarkerOnMap()
}
case .Failure(let error):
print(error)
}
}
}
Basically I just append all received data to my dataFromServer which belongs to dataClass class:
class dataClass: NSObject {
var latitude: Double
var longitude: Double
init(latitude: Double, longitude: Double) {
self.latitude = latitude
self.longitude = longitude
}
}
My getCoordinatesFromServer() function is being called every 3 seconds (for now). What I was expecting to receive new coordinates (and I do receive them for sure), thenshowMarkerOnMap() should be called thus clearing all existing markers and creating news. What I get - marker duplicate and noticeable lag. The original marker disappears if go to another View and then comeback to View containing mapView.
Any suggestion on how to improve my code or some alternative?

Answer 1

If you have any kind of unique identifier for your positions that came from server, you can keep a list of markers and then update their location when new data arrive. Something like this:
for result in json.arrayValue {
let lat = result["latitude"].doubleValue
let lon = result["longitude"].doubleValue
let identifier = result["identifier"] as! String
self.myMarkersDictionary[identifier]?.position.latitude = lat
self.myMarkersDictionary[identifier]?.position.longitude = lon
...
}