firestore fetch subcollection - swift

Question

I'm trying to fetch subcollection of my users document with code below
func readData(){
let userId = Auth.auth().currentUser?.uid
self.db.collection("users/\(userId)/saved").getDocuments { (snapshot, err) in
if let err = err {
print("err")
}
if let userId != nil {
for document in snapshot!.documents {
let docId = document.documentID
let cty = document.get("city") as! String
let ccode = document.get("code") as! String
let countr = document.get("country") as! String
print(cty, ccode, countr,docId)
}
}
}
but my code doesn't print anything, I don't understand the problem, documents exsist, see picture below

Answer 1

You're using illegal syntax with the userId check in the snapshot return but the logic flow is the bigger problem. I would recommend you check if the user is signed in before grabbing the subcollection and checking if there is a viable snapshot instead of checking the state of authentication.
func readData() {
guard let userId = Auth.auth().currentUser?.uid else {
return
}
db.collection("users/\(userId)/saved").getDocuments { (snapshot, error) in
guard let snapshot = snapshot else {
if let error = error {
print(error)
}
return
}
for doc in snapshot.documents {
guard let city = doc.get("city") as? String,
let code = doc.get("code") as? String,
let country = doc.get("country") as? String else {
continue // continue document loop
}
let docId = doc.documentID
print(city, code, country, docId)
}
}
}