Async function not handled by completion handler - ios

Question

I am using the google maps distance matrix api and using a compeletion handler to pass my async function calls like this:
func configureRoute(origin:String,destination:String, completionHandler: #escaping (_ duration:Int) -> ()){
let jsonURL = "https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins=place_id:\(origin)&destinations=place_id:\(destination)&key=MYAPI"
guard let url = URL(string: jsonURL ) else {return}
print(jsonURL)
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data else {return}
do {
let route = try JSONDecoder().decode(Welcome.self, from: data)
// print(self.durations)
completionHandler(route.rows[0].elements[0].duration.value)
}
catch let jsonErr {
}
let dataAsString = String(data: data, encoding: .utf8)
}.resume()
}
and then I try and use that result like so, however my output results are still blank and I am unable to use any of the calls that I have received. I am not that good with compeltion handlers, so if anyone could let me know what I have done wrong?
func majorConfigure() {
permutations(placeID.count, &placeID, origin: startPlaceID, destination: endPlaceID)
for eachArray in finalRoutes {
for i in 0..<(eachArray.count-1) {
configureRoute(origin: eachArray[i], destination: eachArray[i+1]){
duration in
self.durations.append(duration)
}
}
groupedDurations.append(durations)
durations.removeAll()
}
print(groupedDurations)
}
After using Dispatch group this is my updated code:
func majorConfigure(){
permutations(placeID.count, &placeID, origin: startPlaceID, destination: endPlaceID)
let dispatchGroup = DispatchGroup()
for eachArray in finalRoutes{
for i in 0..<(eachArray.count-1){
dispatchGroup.enter()
configureRoute(origin: eachArray[i], destination: eachArray[i+1]){
duration in
self.durations.append(duration)
print(self.groupedDurations)
dispatchGroup.leave()
}
}
dispatchGroup.notify(queue: .main){
self.groupedDurations.append(self.durations)
self.durations.removeAll()
}
}
}
The result when I print groupedDurations is:
[]
[]
[]
[]
[]
[]

Answer 1

give this a try :
func majorConfigure() {
permutations(placeID.count, &placeID, origin: startPlaceID, destination: endPlaceID)
for eachArray in finalRoutes {
for i in 0..<(eachArray.count-1) {
configureRoute(origin: eachArray[i], destination: eachArray[i+1]){
duration in
self.durations.append(duration)
if i == eachArray.count - 1{
groupedDurations.append(durations)
}
if i == eachArray.count - 1 && eachArray == finalRoutes.last! {
print(groupedDurations)
durations.removeAll()
}
}
}
}
}
EDITED ANSWER
You can achieve this in this manner :
var indexFinalRoutes = 0
var indexEachArray = 0
func loopFinalRoutes(){
self.indexEachArray = 0
let eachArray = finalRoutes[indexFinalRoutes]
loopEachArray(eachArray: eachArray) { (success) in
self.indexFinalRoutes = self.indexFinalRoutes + 1
if self.indexFinalRoutes < self.finalRoutes.count - 1{
self.loopFinalRoutes()
}else{
self.indexFinalRoutes = 0
print(self.groupedDurations)
}
}
}
func loopEachArray(eachArray : [String] ,
completion: #escaping (_ success:Bool) -> Void){
if indexEachArray + 1 < eachArray.count - 1 {
configureRoute(origin: eachArray[indexEachArray], destination: eachArray[indexEachArray+1]){
duration in
self.durations.append(duration)
self.indexEachArray = self.indexEachArray + 1
let nextEachArray = self.finalRoutes[self.indexFinalRoutes]
self.loopEachArray(eachArray: nextEachArray, completion: completion)
}
}else{
groupedDurations.append(durations)
durations.removeAll()
completion(true)
}
}
call loopFinalRoutes functuin from your majorConfigure function and you will have the output.