CLGeocoder geocodeAddressString() hitting the limit

Question

Im using MapKit's CLGeocoder().geocodeAddressString() to get the coordinates and county information for a list of addresses. Everything works great as long as the # of requests is under 50. but anything over 50 and im hitting API's limit. Since CLGeocoder calls are asynchronous, i can't easily throttle/control the flow of the calls (calling one address at a time, for instance). How would I do this correctly in the "asynchronous world"? (DISCLAIMER: I'm new to the world of GCD and asynchronous flow control, so I think I might require a more detailed response)

Here's the relevant code:

method of Class Property that calls CLGeocoder on the Property's Adress:

   func initializeCoordinates() {

        let addressForCoords = self.address.getAddress()
        CLGeocoder().geocodeAddressString(addressForCoords, completionHandler: { (placemarks, error) -> Void in
            if error != nil {
                print(error!)
                return
            }
            if placemarks!.count > 0 {
                let placemark = placemarks?[0]
                let location = placemark?.location
                self.coordinates = location?.coordinate

                if let subAdminArea = placemark?.subAdministrativeArea {
                    self.address.county = subAdminArea
                }
            }
        })
    }

and then in the section in the ImportVC that imports all the property's addresses from a textBox (and makes the call to initializeCoordinates method on each Property:

    for line in importText {
        let newAddress = Address()
        let newHouse = Property()

        // parse the tab delimited address for each line of input
        let address = line.components(separatedBy: "\t")
        if address.count == 4 {
            newAddress.street = address[0]
            newAddress.city = address[1]
            newAddress.state = trimState(state: address[2])
            newAddress.zip = address[3]
            newHouse.address = newAddress
            newHouse.initializeCoordinates()
            houses.append(newHouse)
        }
    }

score 2 · Answer 1 · answered Feb 14 '17 at 15:15

I faced a similar problem recently. Replace your for-loop with a recursive function that calls itself at the end. However the trick is to call its self with a 0.2 second delay. I use 0.4 to be on the safe side. This will increase the waiting time for the user, although we have no choice due to the API limit.

CLGeocoder geocodeAddressString() hitting the limit

1 Answers1