How to get GPS-ONLY positions?

The positions from Wi-Fi or Cellular Tower by iPhone CLLocationManager are not acc开发者_如何学Gourate enough for tracking routes. I want only the positions from GPS.

For the moment I use newLocation.horizontalAccuracy in didUpdateToLocation to filter:

if (newLocation.horizontalAccuracy < 0 || newLocation.horizontalAccuracy > 100) return;

because I find that when the location "jump" to an inaccurate position (possibly Cell Tower position), the horizontalAccuracy is 100, so I use 100 to filter it out.

What is the best way of getting GPS-ONLY positions, despite of accuracy?

You can't get GPS-only data. It's my understanding that the CLLocation is calculated based on GPS, cell towers as well as any available wireless networks within range.