Calculate ETA in Swift - ios

Question

I'm attempting to calculate the estimated travel time (walking) between two locations in swift, the user to an annotation.
Here is my current code, it does not throw any errors that crash the program but only returns "Error while requesting ETA"
import UIKit
import MapKit
class LocationObjects: NSObject, MKAnnotation {
/*let userView = CLLocation(latitude: mapView.centerCoordinate.latitude, longitude: mapView.centerCoordinate.longitude)
let annotationPoint = CLLocation(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
let distance = userView.distance(from: annotationPoint)*/
var identifier = "bathroom location"
var title: String?
var coordinate: CLLocationCoordinate2D
var distance: Double
var phoneNumber: String
var addressFinished: String
var estimatedTravelTime: String
// Request ETA function
// Uses user location and destination to send request
// For Estimated time of arrival
class func requestETA(userCLLocation: CLLocation, coordinate: CLLocationCoordinate2D) -> String {
var travelTime = String()
let request = MKDirectionsRequest()
/* Source MKMapItem */
let sourceItem = MKMapItem(placemark: MKPlacemark(coordinate: userCLLocation.coordinate, addressDictionary: nil))
request.source = sourceItem
/* Destination MKMapItem */
let destinationItem = MKMapItem(placemark: MKPlacemark(coordinate: coordinate, addressDictionary: nil))
request.destination = destinationItem
request.requestsAlternateRoutes = false
// Looking for walking directions
request.transportType = MKDirectionsTransportType.walking
// You use the MKDirectionsRequest object constructed above to initialise an MKDirections object
let directions = MKDirections(request: request)
directions.calculateETA { (etaResponse, error) -> Void in
if let error = error {
print("Error while requesting ETA : \(error.localizedDescription)")
travelTime = "Not Available"
}else{
print("No error requesting ETA")
travelTime = "\(Int((etaResponse?.expectedTravelTime)!/60)) min"
}
}
return travelTime
}
init(name:String,lat:CLLocationDegrees,long:CLLocationDegrees,userCLLocation:CLLocation, phone:String, address:String){
title = name
coordinate = CLLocationCoordinate2DMake(lat, long)
distance = Double(String(format: "%.2f", (userCLLocation.distance(from: CLLocation(latitude: lat, longitude: long)))*0.000621371))!
phoneNumber = phone
addressFinished = address
estimatedTravelTime = LocationObjects.requestETA(userCLLocation: userCLLocation, coordinate: coordinate)
}
}
The console looks something like this for an exceedingly long amount of lines
2017-05-26 13:53:51.583 Toilet Locator[2568:181698] didFailWithError Error Domain=GEOErrorDomain Code=-3 "(null)" UserInfo={GEORequestThrottleStateLevel=0, GEORequestThrottleStateResetTimeRemaining=34.019131004810333}
2017-05-26 13:53:51.584 Toilet Locator[2568:181698] didFailWithError Error Domain=GEOErrorDomain Code=-3 "(null)" UserInfo={GEORequestThrottleStateLevel=0, GEORequestThrottleStateResetTimeRemaining=34.018206000328064}
Error while requesting ETA : Directions Not Available
Error while requesting ETA : Directions Not Available
I'm hoping for some guidance, thank you all!
Note: ViewController calls this class to be made many times in a row so not sure if that would cause Apple to reject ETA requests?