Fastest routes using MKDirectionsRequest

Hi there,

The issue I am having is I can't get the walking & automobile transport type working together.

Lets say i have a map showing 10 pins from a distance range between 100meters and 10km around my position

Its either I make a direction request with .walking and I only get walking directions.

or .automobile and I only get driving directions.

So I dont' understand why the api is allowing us to pass a set of transport types.

https://developer.apple.com/reference/mapkit/mkdirectionsrequest/1433152-transporttype

And alternate routes

https://developer.apple.com/reference/mapkit/mkdirectionsrequest/1433154-requestsalternateroutes

Im using

                    let request: MKDirectionsRequest = MKDirectionsRequest()
                    request.source = MKMapItem.forCurrentLocation()
                    request.destination = MKMapItem(placemark: MKPlacemark(coordinate: coordinate, addressDictionary: nil))
                    request.transportType = [.walking, .automobile]
                    request.departureDate = Date()
                    request.requestsAlternateRoutes = true
                    let directions: MKDirections = MKDirections(request: request)
                    directions.calculate { [weak self] response, error in
                        [...]
                    }

Is there a way to get the fastest route, regardless of the transport type ?

Thank you !