Swift 3 - UIView loads every time when adding a location coordinate - ios

Question

I am using firebase as my backend. In this application I have used mapkit and firebase. I want to track the location of user. But when I am doing the location of user is sucessfully uploaded to firebase but in my application the view is reloaded.
my code:-
#IBOutlet weak var map:MKMapView!
let locationManager = CLLocationManager()
var lat = [Double]()
var lon = [Double]()
var ref:DatabaseReference!
var uid = ""
override func viewDidLoad() {
super.viewDidLoad()
map.delegate = self
locationManager.delegate = self
ref = Database.database().reference().child("users").child(uid)
ref.child("locations").queryOrderedByKey().observe(.childAdded, with: { (snapshot) in
print("func snapshot \(snapshot)")
let dict = snapshot.value as! [String:Double]
let lat = dict["latitude"]
let lon = dict["longitude"]
print("latidue = \(lat!)")
print("longitude = \(lon!)")
self.lat.append(lat!)
self.lon.append(lon!)
})
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let location = CLLocationCoordinate2D(latitude: lat.first!,longitude: lon.first!)
let destinationLocation = CLLocationCoordinate2D(latitude: lat.last!, longitude:lon.last!)
let sourcePlacemark = MKPlacemark(coordinate: location, addressDictionary: nil)
let destinationPlacemark = MKPlacemark(coordinate: destinationLocation, addressDictionary: nil)
let sourceMapItem = MKMapItem(placemark: sourcePlacemark)
let destinationMapItem = MKMapItem(placemark: destinationPlacemark)
let sourceAnnotation = MKPointAnnotation()
if let location = sourcePlacemark.location {
sourceAnnotation.coordinate = location.coordinate
}
let destinationAnnotation = MKPointAnnotation()
if let location = destinationPlacemark.location {
destinationAnnotation.coordinate = location.coordinate
}
let directionRequest = MKDirectionsRequest()
directionRequest.source = sourceMapItem
directionRequest.destination = destinationMapItem
directionRequest.transportType = .automobile
let directions = MKDirections(request: directionRequest)
directions.calculate {
(response, error) -> Void in
guard let response = response else {
if let error = error {
print("Error: \(error)")
}
return
}
let route = response.routes[0]
self.map.add((route.polyline), level: MKOverlayLevel.aboveRoads)
let rect = route.polyline.boundingMapRect
self.map.setRegion(MKCoordinateRegionForMapRect(rect), animated: true)
}
let span = MKCoordinateSpanMake(0.05, 0.05)
let region = MKCoordinateRegion(center: location, span: span)
map.setRegion(region, animated: true)
let annotation = MKPointAnnotation()
annotation.coordinate = location
map.addAnnotation(annotation)
}
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
let renderer = MKPolylineRenderer(overlay: overlay)
renderer.strokeColor = UIColor.red
renderer.lineWidth = 4.0
return renderer
}
I don't want to reload my whole view just want to render my mapview whenever new cordinate is uploaded.

Answer 1

Remove code from viewDidAppear and put it inside the observe childAdded callback