ReverseGeocodeLocation completions usage in viewDidLoad() swift4.1 - ios

Question

Swift version: 4.1
Hello I am a bit more than beginner in swift. Working in an "order application by user locations". Which I control user "country" and "city" name by reversegeocodelocation function before user give order. And write those values in firebase realtime database childs.
my data structure is like
-TR
-Ankara
-userID
-Order(consist of user lat, user long, user mail, userOrder)
It is okay I did that users can order and cancel his/her orders. But also I want to check if users close their phone and return the app, the app should check the database and if there is order given by current user uID it must change the button label, buttonToCancelState = true, and image of our mascot.
This is how I get user coord for order and "countrycode" and "city" for data structure name.
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let location = locations [0]
if let coord = manager.location?.coordinate {
userLocation = coord
}
let geoCoder = CLGeocoder()
geoCoder.reverseGeocodeLocation(location) {(placemark, error) in
if error != nil {
print("there is an error")
} else {
var placeMark: CLPlacemark?
placeMark = placemark?[0]
// City
if let city = placeMark?.locality {
self.userCity = city as String
}
// Country
if let country = placeMark?.isoCountryCode {
self.userCountry = country as String
}
}
}
}
And I use these "country" and "city" in "order button" like example;
orderHasBeenCalled = true
buttonLabelText.text = "CANCEL/EDIT"
imgView.image = UIImage(named: "...")
let orderRequestDictionary: [String:Any] = ["..."]
databaseREF.child(userCountry).child(userCity).child(userID!).setValue(orderRequestDictionary)
it works flawlessly user can send order, delete it even when user logout it deleted too, (the whole codes did not included)
now the problem is I want to check if the users have an order when the viewDidLoad() loads for this I am using
if let userID = FirebaseAuth.Auth.auth().currentUser?.uid {
databaseRef.child(userCountry).child(userCity).queryOrdered(byChild: userID!).observe(.childAdded, with: { (snapshot) in
self.OrderHasBeenCalled = true
self.buttonLabelText.text = "CANCEL/EDIT"
self.imgView.image = UIImage(named: "...")
databaseRef.child(self.userCountry).child(self.userCity).removeAllObservers()
})
}
Now the problem is as I read in internet reversegeocode is asynchronous or something like that and as seems it is not ready when the viewDidLoad() load, "code for check if there is order" crash the app because it finds no value to search the names in childs.
Terminating app due to uncaught exception 'InvalidPathValidation', reason: '(child:) Must be a non-empty string and not contain '.' '#' '$' '[' or ']''
To make use of userCountry and userCity in orderbutton I define them before viewDidLoad()
var userCountry = String()
var userCity = String()
I have tried many ways but didn't really figure it out that how can I get reversegeocode completion in viewdidload(). I tried viewDidAppear() too btw but it gives userCountry() and userCity() nil too.
I hope my question is clear and easly understandable. Will be very appreciated if answers will be in that way. Did a lot of researh in the internet some I try, some I did not understand or did not know how can I even try. The last place that my hope shine is stack overflow. Thanks by now for all the people whose Kindly responds my question.

Answer 1

I would change a little the approach. Once working with async functions you must avoid sync request values.
There are several ways to make nested calls from async functions, from your code I arrived at this approach, adapt to your need and it should work.
/////////attention the scope (must be above class declaration)
typealias CompletionGetAddress = (_ userCity : String?, _ userCountry: String?, _ success: Bool) -> Void
var userLocation = CLLocationCoordinate2D()
var locationManager = CLLocationManager()
//
class viewController: ... {
func viewDidLoad() {
yourLocationManager.requestLocation()
// you should implement some code to ensure your userLocation from your locationManager is not nil and a valid location
if let userID = FirebaseAuth.Auth.auth().currentUser?.uid {
if self.userCity != "" {
databaseRef.child(userCountry).child(userCity).queryOrdered(byChild: userID!).observe(.childAdded, with: { (snapshot) in
self.OrderHasBeenCalled = true
self.buttonLabelText.text = "CANCEL/EDIT"
self.imgView.image = UIImage(named: "...")
databaseRef.child(self.userCountry).child(self.userCity).removeAllObservers()
})
} else {
getAddress { (city, country, success) in
if success {
self.userCity = city
self.userCountry = country
databaseRef.child(userCountry).child(userCity).queryOrdered(byChild: userID!).observe(.childAdded, with: { (snapshot) in
self.OrderHasBeenCalled = true
self.buttonLabelText.text = "CANCEL/EDIT"
self.imgView.image = UIImage(named: "...")
databaseRef.child(self.userCountry).child(self.userCity).removeAllObservers()
})
}
}
}
}
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let location = locations [0]
if let coord = manager.location?.coordinate {
userLocation = coord /// attention here
}
}
func getAddress(completion: #escaping CompletionGetAddress) {
let geoCoder = CLGeocoder()
geoCoder.reverseGeocodeLocation(userLocation) {(placemark, error) in
if error != nil {
print("there is an error")
completion(nil, nil, false)
} else {
var city: String = ""
var country: String = ""
var placeMark: CLPlacemark?
placeMark = placemark?[0]
// City
if let c = placeMark?.locality {
city = c
}
// Country
if let c = placeMark?.isoCountryCode {
country = c
}
completion(city, country, true)
}
}
}