Polylines are disappearing when zoom closely - ios

Question

I created seven different polylines. However some of them are disappearing when I zoom in closely. Why it is happening? How can I prevent this?
Here is my polyline renderer:
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
let renderer = MKPolylineRenderer(polyline: overlay as! MKPolyline)
renderer.strokeColor = UIColor(red: 1, green: 1, blue: 1, alpha: 0.9)
renderer.lineWidth = 2.2
return renderer
}
//Thousands of parameters sending as a parameter
func createPathWithPoints(_ points: [MKMapPoint]) {
let arc = MKPolyline(points: points, count: points.count)
mapView.addOverlay(arc)
}
Please help!

Answer 1

I had similar problem with using MKPolyline and below is what I did to fix this.
1) Make sure that you have your mapView delegate in viewDidLoad().
mapView.delegate = self
2) Add your overlay to the map.
mapView.addOverlay(polyLine())
I am using coredata in my project, so if myLocations are empty then I return empty MKPolyline()
private func polyLine() -> MKPolyline {
guard let locations = myLocations else {
return MKPolyline()
}
// Coordinates
let coords: [CLLocationCoordinate2D] = locations.map { location in
let location = location as! Location
return CLLocationCoordinate2D(latitude: location.latitude, longitude: location.longitude)
}
return MKPolyline(coordinates: coords, count: coords.count)
}
3) We have access to rendererFor from MKMapViewDelegate. You can change color and width for polyline.
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
guard let polyline = overlay as? MKPolyline else {
return MKOverlayRenderer(overlay: overlay)
}
// Setup renderer
let renderer = MKPolylineRenderer(polyline: polyline)
renderer.strokeColor = .systemBlue
renderer.lineWidth = 3
return renderer
}