Count distance on polyline swift - ios

Question

I've created a map where you can press a start button. The application will then zoom in to your current location, and update the coordinate every 10 second and insert into an array of coordinates. Once I press the stop button, I've a polyline which draws lines between all coordinates. (Like the image below)
So my question is now:
How can I count the distance the polyline was drawn?
//Draw polyline on the map
let aPolyLine = MKPolyline(coordinates: self.locations, count: self.locations.count)
//Adding polyline to mapview
self.mapView.addOverlay(aPolyLine)
let startResult = self.locations.startIndex
let stopResult = self.locations.endIndex
//Retrieve distance and convert into kilometers
let distance = startResult.distance(to: stopResult)
let result = Double(distance) / 1000
let y = Double(round(10 * result)) / 10
self.KiloMeters.text = String(y) + " km"
My guess is that I cannot use startResult.distnace(to: stopResult) because, if I walk in a circle, the kilometer will show 0? right? I'm not sure, but it still dosent work. Nothing is showing when using the code like I've.

Answer 1

class ViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {
// MARK: - Variables
let locationManager = CLLocationManager()
// MARK: - IBOutlet
#IBOutlet weak var mapView: MKMapView!
// MARK: - IBAction
#IBAction func distanceTapped(_ sender: UIBarButtonItem) {
let locations: [CLLocationCoordinate2D] = [...]
var total: Double = 0.0
for i in 0..<locations.count - 1 {
let start = locations[i]
let end = locations[i + 1]
let distance = getDistance(from: start, to: end)
total += distance
}
print(total)
}
func getDistance(from: CLLocationCoordinate2D, to: CLLocationCoordinate2D) -> CLLocationDistance {
// By Aviel Gross
// https://stackoverflow.com/questions/11077425/finding-distance-between-cllocationcoordinate2d-points
let from = CLLocation(latitude: from.latitude, longitude: from.longitude)
let to = CLLocation(latitude: to.latitude, longitude: to.longitude)
return from.distance(from: to)
}
}