Is there a way to get the ETA for multiple .transportTypes with a single request in MapKit?

Question

I'm trying to deliver a user an ETA for walking if the walk is less than 15 mins, and for driving in other cases. I'd like to do this in a single MKDirections.Request() so that I don't have to recursively call the same function in its completion handler.

I can pass in an array for request.transportType, but I can't get both values back out, even though I can see them in the debugger.

func requestDirections(coordinates:CLLocationCoordinate2D, transitType:MKDirectionsTransportType, completion:@escaping(_ travelTime:Double, _ transportType:String)-> Void){
    var travelTime:Double = -1.0
    let directionRequest = MKDirections.Request()
    directionRequest.source = MKMapItem.forCurrentLocation()
    directionRequest.destination = MKMapItem(placemark: MKPlacemark(coordinate: coordinates))
    directionRequest.transportType = [.automobile, .walking]
    
    let directions = MKDirections(request: directionRequest)
    directions.calculateETA(){(ETA,error)  in
        if(error == nil){
            if(ETA.sortedETAs[0]>15){
                completion(travelTime,"car")
            }else{
                completion(travelTime,"figure.walk")
            }
        }else{
            completion(travelTime, "none")
        }
        
    }
}

Is it possible to do what I'm attempting?

From the debugger, if I right-click and Print Description of Sorted ETAs within the ETA return:

Printing description of ETA.some._sortedETAs:
<__NSArrayM 0x6040003b4dd0>(
<GEOETAResultByType: 0x60b0000a4d80> {
    distance = 14530;
    historicTravelTime = 786;
    "static_travel_time" = 725;
    status = "STATUS_SUCCESS";
    transportType = AUTOMOBILE;
    travelTimeBestEstimate = 784;
},
<GEOETAResultByType: 0x60b0000a4cd0> {
    distance = 13111;
    historicTravelTime = 10362;
    "static_travel_time" = 10362;
    status = "STATUS_SUCCESS";
    transportType = WALKING;
    travelTimeBestEstimate = 10362;
}

Debugger Variable View