Defining the title and the subtitle text of an annotation in Swift

Question

I was watching a course on how to edit maps in Swift and add annotations, but unfortunately the instructor did not talk about how to edit the title and the subtitle of an annotation after adding one on the map, so I wanted to go a little bit further and edit them with my very simple knowledge in Swift.

Here's the code:

import UIKit
import MapKit 

class ViewController: UIViewController, MKMapViewDelegate {

@IBOutlet weak var mapView: MKMapView!

//add


@IBOutlet weak var titleText: UITextField!

@IBOutlet weak var subtitleText: UITextField!
@IBOutlet weak var buttonAdd: UIButton!


//add


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

    //add

    subtitleText.alpha = 0
    titleText.alpha = 0
    buttonAdd.hidden = true


    //add


    // 51.498340, -0.153257
    var latitude:CLLocationDegrees = 51.498340

    var longitude:CLLocationDegrees = -0.153257

    var latDelta:CLLocationDegrees = 0.02

    var lonDelta:CLLocationDegrees = 0.02

    var span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, lonDelta)

    var location:CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude)

    var region:MKCoordinateRegion = MKCoordinateRegionMake(location, span)

    mapView.setRegion(region, animated: true)

    var annotation = MKPointAnnotation()

    annotation.coordinate = location

    annotation.title = "Belgravia"

    annotation.subtitle = "I love you!"

    mapView.addAnnotation(annotation)

    var uilpgr = UILongPressGestureRecognizer(target: self, action: "action:")

    uilpgr.minimumPressDuration = 2.0

    mapView.addGestureRecognizer(uilpgr)

}


let newAnnotation = MKPointAnnotation()


func action(gestureRecognizer:UIGestureRecognizer) {

    var touchPoint = gestureRecognizer.locationInView(self.mapView)

    var newCoordinate:CLLocationCoordinate2D = mapView.convertPoint(touchPoint, toCoordinateFromView: self.mapView)


    newAnnotation.coordinate = newCoordinate

    titleText.alpha = 1
    subtitleText.alpha = 1
    buttonAdd.hidden = false

    mapView.addAnnotation(newAnnotation)

    var uilpgr = UILongPressGestureRecognizer(target: self, action: "action:")

    uilpgr.minimumPressDuration = 2.0

}


func addPoint(sender: AnyObject) {

    newAnnotation.title = titleText.text

    newAnnotation.subtitle = subtitleText.text

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

Every time I try to write text inside these two and then press the addPoint button in the iOS simulator it'll crash unexpectedly

[Maps.ViewController button:]: unrecognized selector sent to instance...