LongPress in MapKit - swift

Question

I am bulding an app in Swift 3.
Everything seams to be working ok however when I longPress in the map it acts like if it was longpressed twice.
I don't know why...
i've made a print inside the longpress, to count the longpresses and every time I longpress (one time) it detects two long presses... why is this happening? Whats wrong with it?
import UIKit
import MapKit
class ViewController: UIViewController, MKMapViewDelegate {
#IBOutlet var map: MKMapView!
var numberOfLongPress : Int = 0
override func viewDidLoad() {
super.viewDidLoad()
let latitude: CLLocationDegrees = 38.925560
let longitude: CLLocationDegrees = -9.229723
let lanDelta: CLLocationDegrees = 0.05
let lonDelta: CLLocationDegrees = 0.05
let span = MKCoordinateSpan(latitudeDelta: lanDelta, longitudeDelta: lonDelta)
let coordinates = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
let region = MKCoordinateRegion(center: coordinates, span: span)
map.setRegion(region, animated: true)
let lpgr = UILongPressGestureRecognizer(target: self, action: #selector(ViewController.longpress(gestureRecognizer:)))
lpgr.minimumPressDuration = 0.5
map.addGestureRecognizer(lpgr)
}
func longpress(gestureRecognizer: UIGestureRecognizer) {
let touchPoint = gestureRecognizer.location(in: self.map)
let coordinate = map.convert(touchPoint, toCoordinateFrom: self.map)
let annotation = MKPointAnnotation()
annotation.coordinate = coordinate
annotation.title = "My Place"
map.addAnnotation(annotation)
print("longpress activated")
numberOfLongPress = numberOfLongPress + 1
print(numberOfLongPress) //detect number of long presses
}
}

Answer 1

Selector is called on every state change, so you better check the state and do what you need to do on .began or .ended.
func longpress(gestureRecognizer: UIGestureRecognizer) {
guard gestureRecognizer.state == .began else { return }
// add annotation
}

Answer 2

Let print the state of gestureRecognizer, you'll see .began and .ended. So let check the state of gestureRecognizer before add an annotation.
func longpress(gestureRecognizer: UILongPressGestureRecognizer) {
if gestureRecognizer.state == began {
// do something here
}
}