How to get an Dictionary from Firebase Firestore in Swift - swift

Question

I wonder how to get an Dictionary from my Firestore. For normal Arrays I've done it like that:
func returnArray(){
let newpath = Firestore.firestore().collection(path)
newpath.addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
return
}
self.Array = documents.map { (queryDocumentSnapshot) -> String in
let data = queryDocumentSnapshot.data()
let Name = data["myField"] as? String ?? ""
return Name
}
}
}
That works perfectly fine. My question is now how I have to change my code that its getting an Array out of the Firebase. I had an idea, but it doesn't work:
func returnDictionary(){
let newpath = Firestore.firestore().collection(path)
newpath.addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
return
}
self.Dictionary = documents.map { (queryDocumentSnapshot) -> // I don't know what to fill here
in
let data = queryDocumentSnapshot.data()
let Name = data["AnzeigeName"] as? String ?? ""
let ID = data["selfID"] as? String ?? ""
return ID: Name
}
}
}
What can I try next?

Answer 1

.map is going to give you an array, but you can use Dictionary's init(uniqueKeysWithValues:) to turn this into a Dictionary:
let dictionary : Dictionary<String,String> = .init(uniqueKeysWithValues: documents.compactMap { queryDocumentSnapshot -> (String,String)? in
let data = queryDocumentSnapshot.data()
if let name = data["AnzeigeName"] as? String, let id = data["selfID"] as? String {
return (id, name)
}
return nil
})
It's important to know that uniqueKeysWithValues will crash if the keys are not in fact unique, so you'd want to check for that first (look at #New Dev's comment about init(_:uniquingKeysWith:) to handle this). I'm also using compactMap to get rid of nil values.
(Note: In Swift, generally variable names are lowercased and type names are uppercased. Going against that pattern can make your code challenging to read for others)

Answer 2

Firestore Example
{
name: "Anonymous"
pet {
name: "Max"
age: "3"
}
}
Query
Firebase.firestore().collection(path).getDocuments { querySnapshot, error in
if let error = error {
print(error.localizedDescription)
} else {
for document in querySnapshot!.documents {
let data = document.data()
let name = data["name"]
let pet = data["pet"] as! Dictionary<String, String>
print("Name: \(name)")
print("Pet-name: \(pet["name"]!)")
print("Pet-age: \(pet["age"]!)")
}