'MKMapView' / 'showsUserLocation = true' causing error with modal segue - ios

Question

I am developing a small map application which allows users to view their current location. I have the relevant code to perform this and it seems to work as expected:
import UIKit
import MapKit
import CoreLocation
class ViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate, UISearchBarDelegate, UIPopoverPresentationControllerDelegate {
// CLlocation
var location: CLLocation!
let locationManager = CLLocationManager()
// Map variables
var searchController:UISearchController!
var annotation:MKAnnotation!
var localSearchRequest:MKLocalSearchRequest!
var localSearch:MKLocalSearch!
var localSearchResponse:MKLocalSearchResponse!
var error:NSError!
var pointAnnotation:MKPointAnnotation!
var pinAnnotationView:MKPinAnnotationView!
// IBOutlets
#IBOutlet weak var placesMap: MKMapView!
// Location function
func locationManager(manager: CLLocationManager, didUpdateqLocations locations: [CLLocation]) {
let location = locations.last
let center = CLLocationCoordinate2D(latitude: location!.coordinate.latitude, longitude: location!.coordinate.longitude)
let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))
self.placesMap.setRegion(region, animated: true)
self.locationManager.stopUpdatingLocation()
}
func locationManager(manager: CLLocationManager, didFailWithError error: NSError)
{
print("Error code: " + error.localizedDescription)
}
override func viewDidLoad() {
super.viewDidLoad()
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
self.placesMap.showsUserLocation = true
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
However, when I launch a modal segue to the 'About' page, from a popover (pictured below), the app crashes:
I viewed the error given to me in the terminal, this was
fatal error: unexpectedly found nil while unwrapping an Optional value
Xcode pointed me to this particular line in my viewDidLoad function:
self.placesMap.showsUserLocation = true
When I delete that particular line from my code, the location feature no longer functions, this is obvious. I have checked the outlet to the MKMapView and it seems to be correct.
I really don't know how to avoid this error, or for certainty what is causing it, so any help is appreciated.

Answer 1

Basically, something is making the placesMap deallocate and then viewDidLoad is being called. You might try making the placesMap optional instead of force unwrapping it, so change the ! to a ? on the property and then chain the optional into the call sites of placesMap, so self.placesMap.showsUserLocation becomes self.placesMap?.showsUserLocation and self.placesMap.setRegion(region, animated: true) becomes self.placesMap?.setRegion(region, animated: true)