How to add overlay path in MKMapView swift - ios

Question

I want to add a overlay path among multiple coordinates in mapview. I tried like below code, but it shows a error of "cannot invoke 'map' with an argument list of type ((CLLocation) -> CLLocationCoordinate2D)". Please let me know how can i fix this ?
My ViewController.swift file
import UIKit
import MapKit
class ViewController: UIViewController, MKMapViewDelegate{
#IBOutlet weak var mapView: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
//For Location 1
let location1 = CLLocationCoordinate2D(
latitude: 51.481188400000010000,
longitude: -0.190209099999947280
)
let annotation1 = MKPointAnnotation()
annotation1.coordinate = location1;
annotation1.title = "Chelsea"
annotation1.subtitle = "Chelsea"
let span = MKCoordinateSpanMake(0.15, 0.15)
let region1 = MKCoordinateRegion(center: location1, span: span)
mapView.setRegion(region1, animated: true)
mapView.addAnnotation(annotation1)
//For Location 2
let location2 = CLLocationCoordinate2D(
latitude: 51.554947700000010000,
longitude: -0.108558899999934510
)
let annotation2 = MKPointAnnotation()
annotation2.coordinate = location2;
annotation2.title = "Arsenal"
annotation2.subtitle = "Arsenal"
let region2 = MKCoordinateRegion(center: location1, span: span)
mapView.setRegion(region2, animated: true)
mapView.addAnnotation(annotation2)
var locations = [CLLocation(latitude: 51.481188400000010000, longitude: -0.190209099999947280), CLLocation(latitude: 51.554947700000010000,longitude: -0.108558899999934510)]
//This line shows error
var coordinates = locations.map({(location: CLLocation) -> CLLocationCoordinate2D in return location.coordinate})
var polyline = MKPolyline(coordinates: &coordinates, count: locations.count)
mapView.addOverlay(polyline)
}
func mapView(mapView: MKMapView!, rendererForOverlay overlay: MKOverlay!) -> MKOverlayRenderer! {
if overlay is MKPolyline {
var polylineRenderer = MKPolylineRenderer(overlay: overlay)
polylineRenderer.strokeColor = UIColor.blueColor()
polylineRenderer.lineWidth = 5
return polylineRenderer
}
return nil
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

This should work:
var coordinates = locations.map {
location in
return location.coordinate
}
One-liner:
var coordinates = locations.map { $0.coordinate }
The problem with your code was that locations is a variable of type [CLLocation!] (note the exclamation mark here), but you are declaring its elements as CLLocation (without the !) in the closure:
(location: CLLocation) -> CLLocationCoordinate2D