ViewController.swift

import UIKit
import CoreLocation

class ViewController: UIViewController {

    @IBOutlet weak var locationLabel: UILabel!

    private let locationManager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.delegate = self
    }
}

extension ViewController: CLLocationManagerDelegate {
    func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
        switch manager.authorizationStatus {
        case .authorizedAlways:
            break
        case .authorizedWhenInUse:
            locationManager.startUpdatingLocation()
        case .denied:
            break
        case .notDetermined:
            locationManager.requestWhenInUseAuthorization()
        case .restricted:
            break
        @unknown default:
            fatalError("@unknown default")
        }
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

        let coordinate = locations.last!.coordinate
        let latitude = coordinate.latitude
        let longitude = coordinate.longitude
        locationLabel.text = "lat: \(latitude), long: \(longitude)"
    }

    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {

        locationLabel.text = "error: \(error.localizedDescription)"
    }
}