Firestore query completion - ios

Question

I'm calling a Firestore query that does come back, but I need to ensure completion before moving on with the rest of the code. So I need a completion handler...but for the life of me I can't seem to code it.
As advised by comments I have tried to use the async / await calls:
function:
// get user info from db
func getUser() async {
self.db.collection("userSetting").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
for document in querySnapshot!.documents {
let userTrust = document.data()["userTrust"] as! String
let userGrade = document.data()["userGrade"] as! String
let userDisclaimer = document.data()["userDisclaimer"] as! String
var row = [String]()
row.append(userTrust)
row.append(userGrade)
row.append(userDisclaimer)
self.userArray.append(row)
// set google firebase analytics user info
self.userTrustInfo = userTrust
self.userGradeInfo = userGrade
}
}
}
}
Called by:
internal func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
FirebaseApp.configure()
db = Firestore.firestore()
Database.database().isPersistenceEnabled = true
Task {
do {
let userInfo = await getUser()
}
} return true }
I used a Task as didFinishLauncingWithOptions is synchronous and not asynchronous
However, the getUser() still isn't completed before didFinishLauncingWithOptions moves on.
I need the data from getUser as the very next step uses the data in the array, and without it I get an 'out of bounds exception' as the array is still empty.
Also tried using dispatch group within the func getUser(). Again with no joy.
Finally tried a completion handler:
func getUser(completion: #escaping (Bool) -> Void) {
self.db.collection("userSetting").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
for document in querySnapshot!.documents {
let userTrust = document.data()["userTrust"] as! String
let userGrade = document.data()["userGrade"] as! String
let userDisclaimer = document.data()["userDisclaimer"] as! String
var row = [String]()
row.append(userTrust)
row.append(userGrade)
row.append(userDisclaimer)
self.userArray.append(row)
// set google firebase analytics user info
self.userTrustInfo = userTrust
self.userGradeInfo = userGrade
completion(true)
}
}
}
}
Nothing works. The getUser call isn't completed before the code moves on. Can someone please help. I've searched multiple times, looked at all linked answers but I can not make this work.I'm clearly missing something easy, please help