在地图上绘制干净的折线

Question

我正在iOS应用上工作，在地图上绘制折线以突出显示用户所采用的路线。我可以毫无问题地绘制多边形线。但是，这条线不是你在Googlemap上看到的简洁线条。正如你在图片中看到的那样，它有点像手绘一样诡异。为大图片道歉，因为我不知道如何在SO中调整它们的大小。

如何在图片中实现如下结果：

这是我负责绘制多边形线的代码：

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    if let location = manager.location {

        if (firstLoad) {
            firstLoad = false
            recentCoordinate = location.coordinate
            mapView.camera = GMSCameraPosition(target: location.coordinate, zoom: Constants.MapView.Zoom, bearing: 0, viewingAngle: Constants.MapView.ViewingAngle)
        }
        else {

            mapView.animateToLocation(CLLocationCoordinate2D(latitude: location.coordinate.latitude,longitude: location.coordinate.longitude))


        }
        // this is suppose to filter out noise. I don't think it's working
        let age = 0 - location.timestamp.timeIntervalSinceNow
        if (age > 120) {
            return;    // ignore old (cached) updates
        }
        if (location.horizontalAccuracy < 0) {
            return;   // ignore invalid updates
        }

        if (location.horizontalAccuracy <= 10){
            // this is a valid update
            // Draw route as user moves along
            path.addCoordinate(CLLocationCoordinate2D(latitude: location.coordinate.latitude,
                longitude: location.coordinate.longitude))
            let polyline = GMSPolyline(path: path)
            polyline.strokeColor = UIColor.redColor()
            polyline.strokeWidth = 3
            polyline.map = mapView

            // Save the coordinates to array
            coordinateArray.append([location.coordinate.latitude, location.coordinate.longitude])

        }


    }

}