Firebase Data Swift - swift

Question

I've got a little problem gaining objects from data base.It contains 4 objects(4 images specifically), they're coming but for some reason they overlap. If I print out query item, the logo shows 4 references to the images which is completely correct but when start setting data up to the image, instead of getting 4 images, I get 16. Is there any way to fix? I though it could be fixed by changing the model from struct to class to avoid duplicating but it didn't work out. Maybe a triple loop causes the problem.
class APIManager {
private init() {}
static let shared = APIManager()
func fetchData(collectionType: CollectionType, completion: #escaping (Document) -> Void) {
let dataBase = self.configureFireBase()
dataBase.collection(collectionType.rawValue).getDocuments { (querySnapshot, error) in
if let error = error {
print("Error received trying to get data: \(error)")
}else{
guard let query = querySnapshot?.documents else {return}
for queryItem in query {
for(name, price) in queryItem.data() {
if name == "field1" {
self.getImage { (sneakerImage) in
let documentToAppend = Document(name: queryItem.documentID, field1: price as? String ?? "", field2: queryItem.documentID, image: sneakerImage)
completion(documentToAppend)
}
}
}
}
}
}
}
private func getImage(imageHandler: #escaping (UIImage)->Void) {
let storage = Storage.storage()
let reference = storage.reference(forURL: "gs://sneakershop-b309a.appspot.com").child("pictures")
reference.listAll { (result, error) in
for item in result.items {
print(item)
item.getData(maxSize: 1024 * 1024) { (data, error) in
if let error = error {
print("error: \(error.localizedDescription)")
}else{
guard let image = UIImage(data: data ?? Data()) else {return}
imageHandler(image)
}
}
}
}
}
private func configureFireBase() -> Firestore {
var db: Firestore!
let settings = FirestoreSettings()
Firestore.firestore().settings = settings
db = Firestore.firestore()
return db
}
}