How to get directions to a MKPointAnnotation - ios

Question

I have created a map that has an MKPointAnnotation which is the single point on the map (besides the users location). I am trying to work out how to amend some existing code I have to get the Driving directions to this point.
This is the code that I use early in the application. At this earlier point in the application I have the following which gives me a CLPlaceMark.
[geocoder geocodeAddressString:location
completionHandler:^(NSArray* placemarks, NSError* error){
if (placemarks && placemarks.count > 0) {
CLPlacemark *topResult = [placemarks objectAtIndex:0];
Collecting directions:
MKDirectionsRequest *request = [[MKDirectionsRequest alloc] init];
[request setSource:[MKMapItem mapItemForCurrentLocation]];
MKPlacemark *mkDest = [[MKPlacemark alloc] initWithPlacemark:topResult];
[request setDestination:[[MKMapItem alloc] initWithPlacemark:mkDest]];
[request setTransportType:MKDirectionsTransportTypeWalking]; // This can be limited to automobile and walking directions.
[request setRequestsAlternateRoutes:NO];
MKDirections *directions = [[MKDirections alloc] initWithRequest:request];
[directions calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
if (!error) {
for (MKRoute *route in [response routes]) {
[self.mapView addOverlay:[route polyline] level:MKOverlayLevelAboveRoads]; // Draws the route above roads, but below labels.
// You can also get turn-by-turn steps, distance, advisory notices, ETA, etc by accessing various route properties.
}
}
}];
Issue
The issue is that later on I seem to only be able to access the self.mapView.annotations. So I have access to the MKPointAnnotation, but I need access to a CLPlacemark for the setDestination on the MKDirectionsRequest.
So the question is how do I get a CLPacemark from a MKPointAnnotation, or is there a different approach to getting directions to a single point without that requirement? Thanks

Answer 1

For the directions request, the MKMapItem needs an MKPlacemark (not a CLPlacemark).
You can create an MKPlacemark directly from coordinates using its initWithCoordinate:addressDictionary: method.
For example:
MKPlacemark *mkDest = [[MKPlacemark alloc]
initWithCoordinate:pointAnnotation.coordinate
addressDictionary:nil];
[request setDestination:[[MKMapItem alloc] initWithPlacemark:mkDest]];

Answer 2

MKPointAnnotation will give you the coordinate, which you can put into CLPlacemark's location.coordinate. I don't think there will be any other readily-available information within an MKPointAnnotation that would be usable in a CLPlacemark.
MKPointAnnotation *annotation = ...;
CLPlacemark *placemark = ...;
placemark.location.coordinate = annotation.coordinate;
Edit: Apologies, I didn't realize that CLPlacemarks are largely read-only. That being said, you can use a reverse-geocode on the coordinate of your MKPointAnnotation in order to get a CLPlacemark. This link has information on how to reverse-geocode to get your CLPlacemark from a CLLocation (populate the location.coordinate with your annotation.coordinate) to look up directions.

Answer 3

You need to use the coordinate property of the MKPointAnnotation and then get the CLPlacemark via CLGeocoder using reverse geocode.
EDIT: Some sample code.
CLLocation *location = [[CLLocation alloc] initWithLatitude:annotation.coordinate.latitude longitude:annotation.coordinate.longitude];
CLGeocoder *geocoder = [CLGeocoder new];
[geocoder reverseGeocodeLocation:location completionHandler:^(NSArray *placemark, NSError *error){
// Grab the placemark
}];
Otherwise you need to cache the CLPlacemark which you can do on your annotation datasource if you like (remember MKAnnotation is a protocol, there is nothing saying you can't add a property to the backing model).