How to calculate distance and time between two CLLocation throughout the whole ride with CloudMade maps?

Question

In my iPhone application I allow the user to choose a destination on the map, then when he starts driving toward the destination I want to give him information like: how long until he reaches the destination and what its current distance from the destination. I'm using CloudMade maps SDK for iPhone and i know there is an API method to get a path between two point that returns also the time and distance between them. Is it OK to call this method every time i get a new location from the CLLocationManager to get the updated time and distance? I assume this method query the CloudMade servers so i don't know if calling it a lot of time is the best way to do this..

Answer 1

Swift version would be:

var startLocation:CLLocation!
var lastLocation: CLLocation!

let distance = startLocation.distanceFromLocation(lastLocation)

Answer 2

For distance

/*
 *  distanceFromLocation:
 *
 *  Discussion:
 *    Returns the lateral distance between two locations.
 */
- (CLLocationDistance)distanceFromLocation:(const CLLocation *)location __OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_3_2);

For getting the time needed, you could calculate it yourself. CLLocation has a speed parameter. Use the distance and the speed to calculate time.