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iOS

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

Extract array from closure in for-in loop before passing through segue

Hi,

I have a closure calculating distances within a for-in loop. This loop produces arrays called distances and journeyTimes, which I can see printing from within the closure.

However, I would like to pass these arrays through to another View Controller via a segue, so I need to be able to access them from outside of the closure.

I know the order is asynchronous, so the segue is passing through an empty array before the loop has had a chance to be populated, but I don't know what the best approach to tackle this problem is.

(I am using a prepare for segue further on in my code to try to pass my arrays, as well as others through)

I have tried dispatchGroup() enter/leave and dispatchGroup.notify to perform a segue, but I can't seem to get away from the closure or passing through an empty array.

Any help is greatly appreciated. Code below:

    @IBAction func calculate(_ sender: Any) {

        for index in 0...coordsOfCollective.count { 

            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)


                } else {
                    print("Error!")
                }

            }
        }
    }

Thanks

Lewis

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello,

You can use a completion handler, when the loop finishes populating the array, it will pass the information.

That's an idea.