CLLocation Manager in Swift to get Location of User

You are missing two things. First, you have to ask for permission using requestAlwaysAuthorization or requestWhenInUseAuthorization(). So your viewDidLoad() should be like this:

var locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.requestAlwaysAuthorization()
    locationManager.startUpdatingLocation()
}

Second, edit your Info.plist as indicated here.