SWIFTUI Firebase Retrieving Subcollection Data - swift

Question

I do understand, that all request from firebase are async.
I have collection tasksCategory -> document -> subcollection tasks
This is my class for getting all created tasks category, there is no problem. Problem is that I need to retrieve all tasks for each category by passing document ID.
class fsTasks: ObservableObject {
#Published var categories = [fsTaskCategory]()
init() {
fsGetTaskCategories()
}
/// Retrieve Tasks Categories For Logged In User
func fsGetTaskCategories() {
db.collection("tasksCategories").addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
print("No documents")
return
}
self.categories = documents.compactMap { queryDocumentSnapshot -> fsTaskCategory? in
return try? queryDocumentSnapshot.data(as: fsTaskCategory.self)
}
}
}
}
I have create another function to retrieve all tasks for each passed document ID
func fsGetTasks(documentID: String, completation: #escaping([fsTask]) -> Void) {
var tasks = [fsTask]()
db.collection("tasksCategories").document(documentID).collection("tasks").addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
print("No documents")
return
}
tasks = documents.compactMap { queryDocumentSnapshot -> fsTask? in
return try? queryDocumentSnapshot.data(as: fsTask.self)
}
completation(tasks)
}
}
Problem is that I do not have any idea, how can I call this function directly in the view of SWIFTUI.
Basically I have first ForEach through the ObservedObject of all categories, then I need to do another foreach for all tasks for each category, but first I need to retrieve data. I need function which return an array with all tasks retrieved from firebase but only when completation handler return data.
If I have function like this
func retrieveAllTasks(categoryID: String) -> [fsTasks] {
var fetchedTasks = [fsTasks]()
fsGetTasks(documentID: categoryID, completation: { (tasks) in
fetcheTasks = tasks
})
return fetchedTasks
}
I was still retrieving only empty array.

Answer 1

This is the issue
func retrieveAllTasks(categoryID: String) -> [fsTasks] {
var fetchedTasks = [fsTasks]()
fsGetTasks(documentID: categoryID, completation: { (tasks) in
fetcheTasks = tasks
})
return fetchedTasks
}
This is an asynchronous function as well (see the closure) and you have to give Firebase time to retrieve the data from the server and handle it within the Firebase closure.
What's happening here is that while you are doing that within the Firebase closure itself, that's not happening within this closure. return fetchedTasks is returning before fetchedTasks = tasks.
I would call the firebase function directly since it doesn't appear you need the middleman retrieveAllTasks function
self.fsGetTasks(documentID: "some_doc", completion: { taskArray in
for task in taskArray {
print(task
}
})
If you do, you need to add an #escaping clause to that as well and not use return fetchedTasks