title: GMSCameraPosition: convert kilometers to zoom level
body: <p>There is a way to convert a distance (in kilometers) into a float zoom level of a GMSCameraPosition?</p>
  
  <p>I have an app where the user specifies a diameter (in kilometers) that he wants to see around the gps checkmark (his position). So, I need to convert that distance (like, 30 km) into a zoom level that fits that distance in kilometers.</p>
  
  <p>I'm very new with Google Maps and didn't find a way to that until now.</p>
  
  <p>Thanks in advance.</p>