Get coordination and city at app launch with Swift

Question

What I'm trying to accomplish is, getting the user's coordination and city at app launch, once the app is in foreground, there is a label display the city.
I'm using the following code to get such information.
When I call the location service from a UIButton after the app launch, everything works as it should. Now my questions are,
1. where I should put the code, to get this data at app launch?
2. is there anything else I should implement? or be aware of?
Thank you all in advance.

import Foundation
import CoreLocation
import AddressBookUI

protocol ParseCityDelegate {
     func populateCurrentCity(city: Locations)
}

class GeoServices: UIViewController, CLLocationManagerDelegate {

var lati = Double()
var long = Double()
let locationManager = CLLocationManager()
var parseLocationDelegate: ParseCityDelegate?
let fetchWeatherData = RequestData()

// Location services
func startUpdateLocation() {
    // Ask for user authorization when getting location
    self.locationManager.requestAlwaysAuthorization()
    self.locationManager.requestWhenInUseAuthorization()

    if CLLocationManager.locationServicesEnabled() {
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters
        locationManager.startUpdatingLocation()
    }
}

// Retrive Geo Coordination
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    let currentCoordination = locationManager.location?.coordinate
    lati = currentCoordination!.latitude
    long = currentCoordination!.longitude
    reverseGeocoding(latitude: lati, longitude: long)
    // Stop update location
    locationManager.stopUpdatingLocation()
}

// Retrive City from coordination
func reverseGeocoding(latitude: CLLocationDegrees, longitude: CLLocationDegrees) {
    let location = CLLocation(latitude: lati, longitude: long)
    CLGeocoder().reverseGeocodeLocation(location, completionHandler: {(placemarks, error) -> Void in
        if error != nil {
            print(error!)
            // Display error message
            let alert = UIAlertController(title: "", message: "Unable to locate your coordination.", preferredStyle: .alert)
            let cancel = UIAlertAction(title: "OK", style: .cancel, handler: nil)
            alert.addAction(cancel)
            self.present(alert, animated: true, completion: nil)
            return
        }
        else if (placemarks?.count)! > 0 {
            let pm = placemarks![0] as CLPlacemark
            let cityName = Locations(City: pm.locality!)

            if self.parseLocationDelegate != nil {
                DispatchQueue.main.async(execute: { () -> Void in
                    self.parseLocationDelegate?.populateCurrentCity(city: cityName)
                })
            }
        }
    })
}
}