iOS location services — save a battery please

When coding for iOS location services:

Set a distance parameter to indicate how accurate the location information needs to be.  If the location only needs to be something like “region” or “nearest city”, setting a location/accuracy value of 3 or 4 KM reduces resource usage.
— the system will recognize that “Cellular Location” is sufficient for this accuracy setting and avoid activating WIFI or GPS when it’s not needed.