iOS Swift - Draw route using multiple coordinates in MKMapView [duplicate] - ios

Question

I'm using this code to connect pins(points on map) with polyline:
CLLocationCoordinate2D coordinates[allLocations.count];
int i = 0;
for (locHolder *location in allLocations) {
coordinates[i] = CLLocationCoordinate2DMake([location.lat floatValue], [location floatValue]);
i++;
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coordinates count:[allLocations count]];
self->polyline = polyline;
[self.mapView addOverlay:self->polyline level:MKOverlayLevelAboveRoads];
But this code connects them over-the-air(ignoring roads), is it possible to connect multiple CLLocationCoordinate2D locations with polyline that follows roads?
**
And a shor sub question,
Is there any difference in performance between [allLocations count] and allLocations.count.
Thanks.

Answer 1

In these days I've came across with the same problem, and looking for answers here and there, I found this answer from Rob very useful for this case.
First, supose you have in your MapViewController, an array of objects containing an origin an a destination, each one being of type CLLocationCoordinate2D
In your MapViewController.h
#property (nonatomic, strong) NSArray *locations;
Then, in the implementation, populate that array with some data that goes like this:
_locations = [NSArray arrayWithObjects:
[RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.595571, -46.684408) destination:CLLocationCoordinate2DMake(-23.597886, -46.673950)],
[RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.597886, -46.673950) destination:CLLocationCoordinate2DMake(-23.597591, -46.666805)],
[RouteObject routeWithOrigin:CLLocationCoordinate2DMake(-23.597591, -46.666805) destination:CLLocationCoordinate2DMake(-23.604061, -46.662728)], nil];
Now that you have your array of origin and destinations, you can start drawing a route between them (from A to B, from B to C and from C to D).
Add a button and then connect an IBAction so in that method you are going to do de magic.
- (IBAction)btnDirectionsPressed:(id)sender {
[self enableUI:NO]; // This method enables or disables all the UI elements that interact with the user
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0); // Create the semaphore
__block NSMutableArray *routes = [[NSMutableArray alloc] init]; // Arrays to store MKRoute objects and MKAnnotationPoint objects, so then we can draw them on the map
__block NSMutableArray *annotations = [[NSMutableArray alloc] init];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
for (RouteObject *routeObject in _locations) {
MKDirectionsRequest *directionsRequest = [MKDirectionsRequest new];
[directionsRequest setTransportType:MKDirectionsTransportTypeAutomobile];
[directionsRequest setSource:[routeObject originMapItem]];
[directionsRequest setDestination:[routeObject destinationMapItem]];
[directionsRequest setRequestsAlternateRoutes:NO];
MKDirections *direction = [[MKDirections alloc] initWithRequest:directionsRequest];
// For each object in the locations array, we request that route from its origin and its destination
[direction calculateDirectionsWithCompletionHandler: ^(MKDirectionsResponse *response, NSError *error) {
if (error) {
NSLog(#"There was an error getting your directions");
return;
}
MKRoute *route = [response.routes firstObject];
[routes addObject:route];
[annotations addObject:[routeObject destinationAnnotation]];
dispatch_semaphore_signal(semaphore); // Send the signal that one semaphore is ready to consume
}];
}
});
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
for (int i = 0; i < _locations.count; i++) {
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER); // Wait until one semaphore is ready to consume
dispatch_async(dispatch_get_main_queue(), ^{ // For each element, dispatch to the main queue to draw route and annotation corresponding to that location
MKRoute *route = routes[i];
[self.mapView addOverlay:route.polyline];
[self.mapView addAnnotation:annotations[i]];
});
}
dispatch_async(dispatch_get_main_queue(), ^{ // Finally, dispatch to the main queue enabling elements and resizing map to show all the annotations
[self enableUI:YES];
[self fitRegionToRoutes];
});
});
}
Hope this help!
Joel.