IOS 计算两个经纬度之间的距离

IOS中计算两个经纬度之间的距离：

-(double)distanceBetweenOrderBy:(double) lat1 :(double) lat2 :(double) lng1 :(double) lng2{

           CLLocation *curLocation = [[CLLocation alloc] initWithLatitude:lat1 longitude:lng1];
           CLLocation *otherLocation = [[CLLocation alloc] initWithLatitude:lat2 longitude:lng2];

            double  distance  = [curLocation distanceFromLocation:otherLocation];
            return  distance;
}