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iOS

Lewis Edmonds
Lewis Edmonds
2,823 Points
Posted by Lewis Edmonds
Lewis Edmonds
2,823 Points

Completion Handler in Swift

I've got a closure calculating distance and time between two points, but I need to extract the values outside of the closure.

I'm pretty sure a completion handler is the way to go, but not too sure how to implement it.

My code:

var completionHandlers: [() -> Void] = []

@IBAction func calculateItinerary(_ sender: Any) {


    for index in 0...coordsOfCollective.count - 2 { /

        let sourceLocation = MKPlacemark(coordinate: coordsOfCollective[index]) 

        let destinationLocation = MKPlacemark(coordinate: coordsOfCollective[index + 1])

        let sourceMapItem = MKMapItem(placemark: sourceLocation)
        let destinationMapItem = MKMapItem(placemark: destinationLocation)


        let request = MKDirectionsRequest()
        request.source = sourceMapItem
        request.destination = destinationMapItem

        request.transportType = .automobile
        request.requestsAlternateRoutes = false


        let directions = MKDirections(request: request)

        directions.calculate { response, error in
            if let route = response?.routes.first {
               print("Distance: \(route.distance/1000) km, ETA: \(route.expectedTravelTime/60) mins")

            self.distances.append(route.distance/1000)
            self.journeyTimes.append(route.expectedTravelTime/60)

                print(self.distances)
                print(self.journeyTimes)

                completionHandlers.append(?????)


            } else {
                print("Error!")
            }

        }
    }

print(completionHandlers)

}

The directions.calculate has a declaration of calculate(completionHandler: @escaping MKDirectionsHandler), so I can see it is an escaping closure. But I don't know how I extract distances and journeyTimes arrays.

I don't have an input names completionHandler, and distances and journeyTimes produce Doubles, which aren't accepted by the completionHandlers array...

Any help is appreciated. Thanks.