How to get centre of the route map using GoogleMaps sdk - ios

Question

I want to display an image at the centre of the route map.
Below is the code used for directions between origin and destination:
let camera1 = GMSCameraPosition.camera(withLatitude: 45.4654, longitude:9.1859, zoom: 0.0)
self.mapView = GMSMapView.map(withFrame: cell.mapView.bounds, camera: camera1)
Alamofire.request(url, method: .post, parameters: nil, encoding: JSONEncoding.default, headers: nil)
.validate()
.responseJSON { response in
switch response.result {
case .success:
print(response.result.value!)
print("Validation Successful")
let dictResponse = response.result.value as! NSDictionary
print(dictResponse)
let aryRoutes = dictResponse .value(forKey:"routes" ) as! NSArray
print(aryRoutes)
var aryOverViewPolyLines :NSArray = []
aryOverViewPolyLines = aryRoutes .value(forKey: "overview_polyline") as! NSArray
print(aryOverViewPolyLines)
let strPoints = (aryOverViewPolyLines.value(forKey: "points") as! NSArray).object(at: 0)
let polygon = GMSPolygon()
polygon.path = GMSPath(fromEncodedPath: strPoints as! String)
print(strPoints)
let rectangle = GMSPolyline.init(path: polygon.path)
rectangle.strokeWidth = 2.0
rectangle.strokeColor = .white
rectangle.map = self.mapView
let mapBounds = GMSCoordinateBounds(path: polygon.path!)
self.mapView.animate(with: GMSCameraUpdate.fit(mapBounds, withPadding: 150.0))
case .failure(let error):
print(response.result.value!)
print(error)
}
}
Any suggestions how to solve this issue.

Answer 1

The solution from #mnabaa works by finding the middle path on the polyline. However, some paths could be a lot longer in distance than others. As a result, the point returned by Mnabaa's solution could end up somewhere a lot closer to the point A than the point B depending on the route. The extension below takes this problem into account:
extension GMSPolyline {
var middlePoint: CLLocationCoordinate2D? {
guard let path = path else {
return nil
}
var intermediatePoints: [CLLocationCoordinate2D] = []
for coordinateIndex in 0 ..< path.count() - 1 {
let startCoordinate = path.coordinate(at: coordinateIndex)
let endCoordinate = path.coordinate(at: coordinateIndex + 1)
let startLocation = CLLocation(latitude: startCoordinate.latitude, longitude: startCoordinate.longitude)
let endLocation = CLLocation(latitude: endCoordinate.latitude, longitude: endCoordinate.longitude)
let pathDistance = endLocation.distance(from: startLocation)
let intervalLatIncrement = (endLocation.coordinate.latitude - startLocation.coordinate.latitude) / pathDistance
let intervalLngIncrement = (endLocation.coordinate.longitude - startLocation.coordinate.longitude) / pathDistance
for intervalDistance in 0 ..< Int(pathDistance) {
let intervalLat = startLocation.coordinate.latitude + (intervalLatIncrement * Double(intervalDistance))
let intervalLng = startLocation.coordinate.longitude + (intervalLngIncrement * Double(intervalDistance))
let circleCoordinate = CLLocationCoordinate2D(latitude: intervalLat, longitude: intervalLng)
intermediatePoints.append(circleCoordinate)
}
}
return intermediatePoints[intermediatePoints.count / 2]
}
}
It's based on the article by Dylan Maryk.

Answer 2

func mapView(_ mapView: GMSMapView, didTap overlay: GMSOverlay) {
if let route = overlay as? GMSPolyline{
let coordinate = route.path!.coordinate(at: (route.path!.count()-1) / 2)
route.customMapInfoMarker!.position = CLLocationCoordinate2D(latitude: coordinate.latitude, longitude: coordinate.longitude)
route.customMapInfoMarker.groundAnchor = CGPoint(x: 0.5, y: 0.5)
route.customMapInfoMarker.map = mapView
route.customMapInfoMarker.iconView = // YOUR CUSTOM IMAGEVIEW HERE
}
}
Extend GMSPolyline
extension GMSPolyline{
fileprivate struct AssociatedKey {
static var infoMarker = GMSMarker()
}
var customMapInfoMarker: GMSMarker! {
get {
if let marker = objc_getAssociatedObject(self, &AssociatedKey.infoMarker) as? GMSMarker {
return marker
}
return GMSMarker()
}
set (newValue){
if let newValue = newValue {
objc_setAssociatedObject(
self,
&AssociatedKey.infoMarker,
newValue,
objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
}
}
}
}