Distance between 2 or more drop pins

I was doing a small assignment,in which i was finding the distance between Green drop pin and red drop pins.The green pin shows 开发者_Go百科the user location and red pins shows his friend's location.But i don't have any idea how can do it?So please if somebody help me regarding my problem,I shall be thankful.

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You can try using distanceFromLocation:.

Pls go through the Reference

Update:

// Assumption: lat1, lon1 and lat2, lon2 are double values containing the coordinates

CLLocation *firstLocation = [[[CLLocation alloc] initWithLatitude:lat1 longitude:lon1] autorelease];
CLLocation *secondLocation = [[[CLLocation alloc] initWithLatitude:lat2 longitude:lon2] autorelease];
CLLocationDistance distance = [secondLocation distanceFromLocation:firstLocation];