How to fix geocodeAddressString closure in for each - swift

Question

I have task model in database (using realm), which consists of id, title, distance, longitude, latitude, customerAddress. I'm trying update my distance to task. I'm new to swift so I do not understand how should I fix geoCoder.geocodeAddressString closure, so that all tasks would update with their distance. (when task does not have latitude and longitude I check if task has customeradress by using geocodeAddressString
func updateTasksDistance() {
// get tasks for db
guard let tasks = Task.getAllUserTasks() else { return }
// last tracked location
guard let lastLocation = lastLocation else { return }
let myLocation = CLLocation(latitude: lastLocation.coordinate.latitude, longitude: lastLocation.coordinate.longitude)
var distance = 0
tasks.forEach({ (task) in
// check if task has longitude and latitude
if let lat = Double(task.latitude), let long = Double(task.longitude), lat != 0 && long != 0 {
let taskLocation = CLLocation(latitude: lat, longitude: long)
distance = Int(taskLocation.distance(from: myLocation))
} else if !task.customerAddress.isEmpty { // check if task has address
geoCoder.geocodeAddressString(task.customerAddress) { placemarks, _ in
if let placemark = placemarks?.first, let location = placemark.location {
self.taskLocationCoordinate = CLLocation(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude )
}
}
}
// check if we have closure location??
if let taskLocation = taskLocationCoordinate {
distance = Int(CLLocation(latitude: taskLocation.coordinate.latitude, longitude: taskLocation.coordinate.longitude).distance(from: myLocation))
taskLocationCoordinate = nil
}
// update my distance to task
updateTaskDistanceDb(task: task, with: distance)
// reset distance
distance = 0
})
}
// update task distance in db
fileprivate func updateTaskDistanceDb(task: Task, with distance: Int) {
let realm = try? Realm()
if let realm = realm {
do {
try realm.write {
task.distance = distance
}
} catch {
print("error")
}
}
}
Current result: distance gets updated correctly where closure is not called, but when closure is getting called then I get out of order results
expected result: all tasks distance relative to mine updated correctly

Answer 1

Fixed this issue by using this code:
fileprivate func geoCode(addresses: [String], results: [CLPlacemark] = [], completion: #escaping ([CLPlacemark]) -> Void ) {
guard let address = addresses.first else {
completion(results)
return
}
let geoCoder = CLGeocoder()
geoCoder.geocodeAddressString(address) { placemarks, _ in
var updatedResults = results
if let placemark = placemarks?.first {
updatedResults.append(placemark)
}
let remainingAddresses = Array(addresses[1..<addresses.count])
self.geoCode(addresses: remainingAddresses, results: updatedResults, completion: completion)
}
}
func updateTasksDistance() {
// get tasks for db
guard let tasks = Task.getAllUserTasks() else { return }
// last tracked location
guard let lastLocation = lastLocation else { return }
let myLocation = CLLocation(latitude: lastLocation.coordinate.latitude, longitude: lastLocation.coordinate.longitude)
let dispatchGroup = DispatchGroup()
for task in tasks where !task.customerAddress.isEmpty {
let addresses = [task.customerAddress]
dispatchGroup.enter()
geoCode(addresses: addresses) { results in
guard let customerAdress = results.first else { return }
guard let customerLocatin = customerAdress.location else { return }
let taskLocation = CLLocation(latitude: customerLocatin.coordinate.latitude,
longitude: customerLocatin.coordinate.longitude )
// do additional sutff
dispatchGroup.leave()
}
}
dispatchGroup.notify(queue: DispatchQueue.main, execute: {
// got all the address
}
})
}
Recursive geocode function helped to calculate all coordinates and dispatchGroup.notify is for waiting till all addresses are geocoded.