Swift Firebase Reuse a function throughout the app - swift

Question

In my app, in a few places I am loading data from Firebase Firestore database and showing the data. The problem is I am not adopting the DRY technique and I know I shouldn't, but I am reusing this same load function in different places in my app.
func loadData() {
let user = Auth.auth().currentUser
db.collection("users").document((user?.uid)!).collection("children").getDocuments() {
QuerySnapshot, error in
if let error = error {
print("\(error.localizedDescription)")
} else {
// get all children into an array
self.childArray = QuerySnapshot!.documents.flatMap({Child(dictionary: $0.data())})
DispatchQueue.main.async {
self.childrenTableView.reloadData()
}
}
}
}
The function simply grabs all the children from the database and adds them to my child array.
Is there some better way to do this or a central place I can put this function where it can be called as and when I need it in the app instead of repeatedly adding it in multiple view controllers?
I thought about a helper class, and just calling the function, but then not sure how to add the result to the childArray in the viewcontroller I needed it?
my Child model
import UIKit
import FirebaseFirestore
protocol DocumentSerializable {
init?(dictionary:[String:Any])
}
// Child Struct
struct Child {
var name: String
var age: Int
var timestamp: Date
var imageURL: String
var dictionary:[String:Any] {
return [
"name":name,
"age":age,
"timestamp":timestamp,
"imageURL":imageURL
]
}
}
//Child Extension
extension Child : DocumentSerializable {
init?(dictionary: [String : Any]) {
guard let name = dictionary["name"] as? String,
let age = dictionary["age"] as? Int,
let imageURL = dictionary["imageURL"] as? String,
let timestamp = dictionary["timestamp"] as? Date else {
return nil
}
self.init(name: name, age: age, timestamp: timestamp, imageURL: imageURL)
}
}

Answer 1

EDIT: I have updated to safely unwrap the optionals. You may still have to modify as I am not sure what your Firebase structure is, nor do I know your Child initializer.
You could just write this as a static function and then reuse it everywhere. I assume you might have some class related to whatever "children" is, and that'd be the best place to implement. You could pass the results (as an option array of Child) in a completion handler so that you can do whatever you need with those results. It'd look something like this:
static func loadData(_ completion: (_ children: [Child]?)->()) {
guard let user = Auth.auth().currentUser else { completion(nil); return }
Firestore.firestore().collection("users").document(user.uid).collection("children").getDocuments() {
querySnapshot, error in
if let error = error {
print("\(error.localizedDescription)")
completion(nil)
} else {
guard let snapshot = querySnapshot else { completion(nil); return }
// get all children into an array
let children = snapshot.documents.flatMap({Child(dictionary: $0.data())})
completion(children)
}
}
}
Assuming you have this implemented in your Child class you would use it like this:
Child.loadData { (children) in
DispatchQueue.main.async {
if let loadedChildren = children {
//Do whatever you need with the children
self.childArray = loadedChildren
}
}
}