Swift MapView Stuck Around User's Current Location - swift

Question

Currently, my code drops a pin on the user's current location. There is one small problem when I try to move the map around, because the view will shift back and be centered around that current location pin. I want the user be able to navigate the map and move it around, and if the user switches view controllers (goes to another tab) and comes back, the map will be centered around the user location pin. I have been trying to modify this code to do this, but I have not had any luck where to start.
import UIKit
import MapKit
import CoreLocation
let newPin = MKPointAnnotation()
class MapVC: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {
#IBOutlet weak var map: MKMapView!
let locationManager = CLLocationManager()
override func viewDidLoad() {
super.viewDidLoad()
// User's location
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
if #available(iOS 8.0, *) {
locationManager.requestAlwaysAuthorization()
} else {
// Fallback on earlier versions
}
locationManager.startUpdatingLocation()
// add gesture recognizer
let longPress = UILongPressGestureRecognizer(target: self, action: #selector(MapVC.mapLongPress(_:))) // colon needs to pass through info
longPress.minimumPressDuration = 1.5 // in seconds
//add gesture recognition
map.addGestureRecognizer(longPress)
}
// func called when gesture recognizer detects a long press
func mapLongPress(_ recognizer: UIGestureRecognizer) {
print("A long press has been detected.")
let touchedAt = recognizer.location(in: self.map) // adds the location on the view it was pressed
let touchedAtCoordinate : CLLocationCoordinate2D = map.convert(touchedAt, toCoordinateFrom: self.map) // will get coordinates
let newPin = MKPointAnnotation()
newPin.coordinate = touchedAtCoordinate
map.addAnnotation(newPin)
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
map.removeAnnotation(newPin)
let location = locations.last! as CLLocation
let center = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))
//set region on the map
map.setRegion(region, animated: true)
newPin.coordinate = location.coordinate
map.addAnnotation(newPin)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

Your code has several problems:
You declare a variable newPin at global scope and in mapLongPress(...) you declare a new variable let newPin = ... locally so the global newPin isn't used.
In didUpdateLocations() you first remove the (global) newPin annotation (why??) and set it again at the end of the function. Because the global newPin was never set to anything useful this will never get the desired result.
Furthermore, in didUpdateLocations() you set the map's region and center point to the current location. This is done on every location update, giving weird results when trying to pan the map.
To set center and region when the view appears, try something like that:
class MapVC: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {
#IBOutlet weak var map: MKMapView!
let locationManager = CLLocationManager()
// class variable for the current location
var lastLocation: CLLocation?
override func viewDidLoad() {
// ...
}
override func viewDidAppear(_ animated: Bool) {
if self.lastLocation != nil {
// set center and region to current location
let center = CLLocationCoordinate2D(latitude: self.lastLocation.coordinate.latitude, longitude: self.lastLocation.coordinate.longitude)
let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))
//set region on the map
map.setRegion(region, animated: true)
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
self.lastLocation = locations.last
}
}