How to clear polyline as the user walks through the road (polyline) - swift

Question

I am new to maps technology .
I am using google apis to the the json data to fetch the routes on the map using the polyline .
I need some help regarding the polyline . I want to clear the path of polyline as per users drives through the route . I tried searching many solutions but couldnt worked for me .
I have attached an image for the same ...
Function to draw polyline ---
func drawPath(from polyStr: String){
print("inside Drawpath")
path = GMSPath(fromEncodedPath: polyStr)!
let polyline = GMSPolyline(path: path)
polyline.strokeWidth = 6
polyline.map = myMapView // Google MapView
polyline.strokeColor = UIColor(red: 0, green: 128/255, blue: 1, alpha: 1)
// let camera = GMSCameraUpdate.fit(GMSCoordinateBounds(coordinate: CLLocationCoordinate2D(latitude: Double(lat), longitude: Double(long)), coordinate: CLLocationCoordinate2D(latitude: Double(directionlat)!, longitude: Double(directionlat)!)))
let cameraUpdate = GMSCameraUpdate.fit(GMSCoordinateBounds(coordinate: CLLocationCoordinate2D(latitude: Double(lat), longitude: Double(long)), coordinate: CLLocationCoordinate2D(latitude: Double(directionlat)!, longitude: Double(directionlat)!)))
// self.timer = Timer.scheduledTimer(timeInterval: 0.003, target: self, selector: #selector(animatePolylinePath), userInfo: nil, repeats: true)
//myMapView.moveCamera(cameraUpdate)
let currentZoom = myMapView.camera.zoom
// myMapView.animate(toZoom: currentZoom - 1.4)
}
Any help is appreciated .
Thanks and regards

Answer 1

I have faced the same issue and I found a solution which works fine in my current 2 projects. So let me share my idea here.
first, get the initial polypathString from the direction API. Now you can get the number of points in the path by using GMSPath object and by combining that with CLLocation.distance method I have tried to find whether the driver is in the path.
If he is found on the path
I take the index from array in which the driver is close and start drawing from there
else
I request to fetch an another direction API since he is not the path drawing it is not right.
let polyPath = GMSPath.init(fromEncodedPath: pathStr)!
func isPathChanged(byDriver coordinate : CLLocation) -> Bool{
guard self.path.count() != 0 else{return true}
for range in 0..<path.count(){
let point = path.coordinate(at: range).location//CLLocation
if point.distance(from: coordinate) < 75{
self.driversPositiionAtPath = range
return false
}
}
self.driversPositiionAtPath = 0
return true
}
not just do the magic trick
Note: I am maintaining a variable to store the driver's position at polyline driversPositiionAtPath
if isPathChanged(byDriver : driversLocation){
self.wsToFetchNewPathFromDirection()
}else{
self.drawRoute(for : polyPath )
}
func drawRoute(for path : GMSPath){
let drawingPath = GMSMutablePath()
for i in self.driversPositiionAtPath..<path.count(){
drawingPath.add(path.coordinate(at: i))
}
self.polyline.path = drawingPath
self.polyline.strokeColor = UIColor.black
self.polyline.strokeWidth = 3.0
self.polyline.map = mapLocation
}
Check if driver is on the path or not, once he moves or every 10 seconds.
happy codding !