Annotations not showing on map - json

Question

I'm trying to add annotations on the map using a list of locations coming from the server.
Json Data:
[{ "_id" : "589f3e299b64795df23a886b",
"name" : "Store 1",
"description" : "Most awesome store!",
"location" : {
"longitude" : -6.279025369998967,
"latitude" : 53.35487382895707
}
},
{
"_id" : "589f3e299b64795df23a886b",
"name" : "Store 2",
"description" : "Most awesome store!",
"location" : {
"longitude" : -6.267085527951536,
"latitude" : 53.33785738724761
}
}]
I am using alamo fire to send a get request from the server to get the json data above in the viewWillAppear method.
override func viewWillAppear(_ animated: Bool) {
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestWhenInUseAuthorization()
locationManager.requestLocation()
mapView.showsUserLocation = false
var currentLocation = Location()
if let location = locationManager.location {
currentLocation = Location(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
}
//default to 10 km radius for now
let params = [
"latitude": currentLocation.getLatitude(),
"longitude": currentLocation.getLongitude(),
"radius": 10.0
] as [String : Any]
Alamofire.request("http://website.com/fyp/searchNearbyStores", parameters: params).responseJSON { response in
switch response.result {
case .success(let value):
let result = JSON(value)
print(result)
self.storeList = result.arrayValue.map({
Store(name: $0["name"].stringValue, description: $0["description"].stringValue, location: CLLocationCoordinate2D(latitude: $0["location"]["latitude"].doubleValue, longitude: $0["location"]["longitude"].doubleValue))
})
case .failure(let error):
print(error)
}
}
}
And finally in the viewDidLoad method I use the storeList with the lat/long data to add the annotations.
override func viewDidLoad() {
super.viewDidLoad()
//zoom to current user location
if let location = locationManager.location {
let span = MKCoordinateSpanMake(0.01, 0.01)
let region = MKCoordinateRegion(center: location.coordinate, span: span)
mapView.setRegion(region, animated: true)
}
for store in storeList {
let annotation = MKPointAnnotation()
annotation.title = store.getName()
annotation.subtitle = store.getDescription()
annotation.coordinate = store.getLocation()
mapView.addAnnotation(annotation)
}
}
For some reason the annotations doesnt seem to show in the map when I run it. I seem to be doing the right way of adding annotations but maybe missed a small but important bit. Can anyone help?

Answer 1

You are using viewWillAppear wrong. You should make a request in viewDidLoad and do this inside request function (after data is loaded)
if let location = locationManager.location {
let span = MKCoordinateSpanMake(0.01, 0.01)
let region = MKCoordinateRegion(center: location.coordinate, span: span)
mapView.setRegion(region, animated: true)
}
for store in storeList {
let annotation = MKPointAnnotation()
annotation.title = store.getName()
annotation.subtitle = store.getDescription()
annotation.coordinate = store.getLocation()
mapView.addAnnotation(annotation)
}
because viewDidLoad is called before viewWillAppear, and because Alamofire request is async, which means, that it will be finished after viewDidLoad and viewWillAppear. So what happens is your array is empty, when you add annotations, and when your data is downloaded - nothing happens