Add annotation after retrieving users latitude and longitude from Firebase - ios

Question

I am trying to add a mapView annotation of all the online user after retrieving their latitude and longitude from Firebase. I am able to print it as an optional or as a CLLocationDegrees aka Double, but when I try to add it into my user.userAnnotation attribute I get a fatal error. This is what I am printing:
this is the users lat Optional(19.435477800000001)
this is the user latitude in CLLocationDegrees 19.4354778
fatal error: unexpectedly found nil while unwrapping an Optional value
And this is my function:
func fetchOnlineUsers() {
ref = FIRDatabase.database().reference()
FIRDatabase.database().reference().child("users").observe(.childAdded, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let user = AppUser()
user.userEmail = (snapshot.value as? NSDictionary)?["name"] as? String
user.latitude = (snapshot.value as? NSDictionary)?["latitude"] as? Double
user.longitude = (snapshot.value as? NSDictionary)?["longitude"] as? Double
user.online = ((snapshot.value as? NSDictionary)?["online"] as? Bool)!
print("this is the user latitude \(user.latitude)")
let userLat = CLLocationDegrees(user.latitude!)
let userLon = CLLocationDegrees(user.longitude!)
if user.online == true {
user.userAnnotation.coordinate = CLLocationCoordinate2D(latitude: userLat, longitude: userLon)
self.users.append(user)
}
print("this are the users \(self.users)")
print("this is the dictionary \(dictionary)")
self.mainMapView.addAnnotations([user.userAnnotation])
}
}, withCancel: nil)
}

Answer 1

Well some of the value/s that you´re getting is nil. Try this instead:
guard let dictionary = snapshot.value as? [String: AnyObject],
let email = (snapshot.value as? NSDictionary)?["name"] as? String,
let latitude = (snapshot.value as? NSDictionary)?["latitude"] as? Double,
let longitude = (snapshot.value as? NSDictionary)?["longitude"] as? Double,
let online = ((snapshot.value as? NSDictionary)?["online"] as? Bool)! else { // Some error }
If this succeeds you can start use the variables created in the guard let and they will 1: have a value, 2: not be Optional.