MKMapView MKTileOverlay擦除MKPolyline层

Question

我正在将此SDK用于地图 https://github.com/2gis/iOS-SDKs-for-tiles 但是我添加的路线不可见。 rendererFor调用，但行不可见。如果我删除MKTileOverlay，一切正常。我该如何解决？

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {

        if (overlay is MKPolyline) {
            let pr = MKPolylineRenderer(overlay: overlay)
            pr.strokeColor = UIColor.blue.withAlphaComponent(1.0)
            pr.lineWidth = 5
            return pr
        } else {
            return MKTileOverlayRenderer(overlay: overlay)
        }

    }