Swift 3 and Firebase - Cannot add annotations with firebase array, prints to console though

Question

In my console, I can access Firebase latitude, longitude, and name of restaurant. I have a few print statements that I use to test that I am getting the values I needed. When I try to assign these values into an annotation.coordinate = CLLocationCoordinate2DMake(with the respective info here) I still can't get this function to print in maps.

I mainly created a function so that I can call it in viewDidLoad() so that everything I want automatically comes up when this page of the app loads.

I also created an action for a button so that when a user clicks a button on shown on the view controller, it also prints the location but THAT case also is not working. When I make coordinates I also do not know if I need ! on res.latitude and res.longitude!…. When I take it off it still does not work. A previous project I created I added annotations the same way I did here MINUS the firebase array. I created one myself with struct variables (title, latitude, longitude) in them that are later called.

import UIKit
import Firebase
import FirebaseStorage
import FirebaseDatabase
import MapKit
import CoreLocation

class MapViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {//add last 2 delegates/protocols.conforming

   //firebase refrences
   var dataBaseRef: FIRDatabaseReference! {
   return FIRDatabase.database().reference()
}

var storageRef: FIRStorageReference! {
    return FIRStorage.storage().reference()
}
var restaurantArray = [Restaurant]()


@IBOutlet weak var mapView: MKMapView!
@IBOutlet weak var segments: UISegmentedControl!

let locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()

    title = "Maps"
    navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Main Menu", style: .plain, target: self, action: #selector(SSASideMenu.presentLeftMenuViewController))


    self.locationManager.delegate = self//as soon as loaded find location--conforms to delegate
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest//best location
    self.locationManager.requestWhenInUseAuthorization()//only want location when using app
    self.locationManager.startUpdatingLocation()//turn on location manager..make location start looking
    self.mapView.showsUserLocation = true//shows blue dot

    displayRestaurants()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)
    fetchRestaurants()
    displayRestaurants()
}
//see if you want to give it a try!!!!!!!!!!!!!!!
func fetchRestaurants(){
    FIRDatabase.database().reference().child("AthensRestaurants/Restaurants").observe(.value, with: { (snapshot) in
        var results = [Restaurant]()

        for res in snapshot.children{
            let res = Restaurant(snapshot: res as! FIRDataSnapshot)
            results.append(res)
        }
        self.restaurantArray = results
    }) { (error) in
        print("error encountered dumbass")
        print(error.localizedDescription)
    }
}
  //work here!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
func displayRestaurants(){

    //array already created--using a firebase array


    for res in restaurantArray {
        let annotation = MKPointAnnotation()
        annotation.title = res.name
        print(res.name)
        let x = res.latitude //shows that this works and I can retrieve data!!!
        print (x! as Double)
        let y = res.longitude
        print(y! as Double)
        annotation.coordinate = CLLocationCoordinate2D(latitude: res.latitude!, longitude: res.longitude!) //Should the exclamation marks be there "!"
        mapView.addAnnotation(annotation)
    }
}


//A way of testing
@IBAction func test12(sender: UIButton) {
    displayRestaurants() //another way i tried makiing anotations show....!!!!!!!!!
}


//below works on seperate projects
//MARK: - Location Delegate Methods
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {//didupdate is contiously called so below is continuously called
    let location = locations[0]
    let span = MKCoordinateSpanMake(0.01, 0.01)

    let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
    let region = MKCoordinateRegionMake(myLocation, span)//lat long--region that we want map to scope to--parameters is closeness zoom
    self.mapView.setRegion(region, animated: true)//since we have thise we can stop updating eventually
    self.locationManager.stopUpdatingLocation()

}

//check for errors
func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {//should be NSError but
    print("Errors:" + error.localizedDescription)
    //displayRestaurants()
}
//segment changer for terrain, hybrid, and regular---just allows different types of map views
@IBAction func segChange(_ sender: Any) {
    switch segments.selectedSegmentIndex {
    case 0:
        mapView.mapType = MKMapType.standard
        break
    case 1:
        mapView.mapType = MKMapType.satellite
        break
    case 2:
        mapView.mapType = MKMapType.hybridFlyover
        break
    default:
        break
    }
}   
}