distanceFromLocation - Calculate distance between two points

Question

Just a quick question on Core Location, I\'m trying to calculate the distance between two points, code is below:

    -(void)locationChange:(CLLocation *)newL         


        

Answer 1

The problem here is that you're calling an object method:

- (CLLocationDistance)distanceFromLocation:(const CLLocation *)location;

of class CLLocation.

CLLocationCoordinate2D is in fact a structure, consisting of two doubles:

typedef struct
{
    CLLocationDegrees latitude;
    CLLocationDegrees longitude;
} CLLocationCoordinate2D;

Proper way of doing this is to get a CLLocation object and call distanceFromLocation on it. Like this:

CLLocation* newLocation;
CLLocation* oldLocation;
CLLocationDistance distance = [newLocation distanceFromLocation:oldLocation];

Of course you first need to initialize both of those values (from CLLocationManager, for instance).