cllocation getDistanceFrom/distanceFromLocation

Question

Hi all,

i've define a cllocation var and if nil, i'll give my newlocation value in delegate

-(void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation
        fromLocation:(CLLocation *)oldLocation {
    if (myStart == nil) {
        self.myStart = newLocation;

when i call

    if ([myStart respondsToSelector:@selector(distanceFromLocation:)]){
    distance = [myStart distanceFromLocation:newLocation];
} else if ([myStart respondsToSelector:@selector(getDistanceFrom:)]){
    distance = [myStart getDistanceFrom:newLocation];
}
totaldistance.text = [NSString stringWithFormat:@"%5.2fkm", distance / 1000] ;

starting point starts ever from a value that is not "0.00".

in which way i can do?