我怎样才能获得最短的路线？

Question

我想展示最短的路线。假设我在plist文件中有5个目的地，这意味着我有5条路线，但我想显示距离最短的目的地。

我写的以下代码并没有完成。

 NSString *thePath = [[NSBundle mainBundle] pathForResource:@"ROUTE_TRIP_1" ofType:@"plist"];
    NSArray *pointsArray = [NSArray arrayWithContentsOfFile:thePath];

    NSInteger pointsCount = pointsArray.count;

    CLLocationCoordinate2D pointsToUse;

    for(int i = 0; i < pointsCount; i++) {
        CGPoint p = CGPointFromString(pointsArray[i]);
        pointsToUse = CLLocationCoordinate2DMake(p.x,p.y);
      //  NSLog (@"total11 %.1f",_currentRoute.distance/1000);
        NSLog (@"total %.1f",_currentRoute.distance/1000);}
    //*********************************************************
   // CLLocationCoordinate2D destinationCoords = CLLocationCoordinate2DMake(13.702668,100.488366);
    MKPlacemark *destinationPlacemark = [[MKPlacemark alloc] initWithCoordinate:pointsToUse addressDictionary:nil];
   // MKPlacemark *destinationPlacemark = [[MKPlacemark alloc] initWithCoordinate:destinationCoords addressDictionary:nil];
    MKMapItem *destination = [[MKMapItem alloc] initWithPlacemark:destinationPlacemark];
        [directionsRequest setDestination:destination];

        MKDirections *directions = [[MKDirections alloc] initWithRequest:directionsRequest];
    [directions calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
        // We're done
        self.activityIndicator.hidden = YES;
        [self.activityIndicator stopAnimating];
        self.routeButton.enabled = YES;

       // Now handle the result
        if (error) {
            NSLog(@"There was an error getting your directions");
            //return;
        }


        // So there wasn't an error - let's plot those routes
        self.routeDetailsButton.enabled = YES;
        self.routeDetailsButton.hidden = NO;
        _currentRoute = [response.routes firstObject];
        [self plotRouteOnMap:_currentRoute];

        }
}];