ios - How to add overlay path in MKMapView swift -

i want add overlay path among multiple coordinates in mapview. tried below code, shows error of "cannot invoke 'map' argument list of type ((cllocation) -> cllocationcoordinate2d)". please let me know how can fix ?

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 mkpolyline {             var polylinerenderer = mkpolylinerenderer(overlay: overlay)             polylinerenderer.strokecolor = uicolor.bluecolor()             polylinerenderer.linewidth = 5             return polylinerenderer         }          return nil     }      override func didreceivememorywarning() {         super.didreceivememorywarning()         // dispose of resources can recreated.     } } 

this should work:

var coordinates = locations.map {     location in     return location.coordinate } 

one-liner:

var coordinates = locations.map { $0.coordinate } 

the problem code locations variable of type [cllocation!] (note exclamation mark here), declaring elements cllocation (without !) in closure:

(location: cllocation) -> cllocationcoordinate2d