Initialize Class from Firebase Data Pull - ios

Question

I'm trying to create a class with a failable initializer that takes a FIRUser and FIRDatabaseReference. It downloads the data from the Firebase database and sets its own variables based on what is returned. Else, the initializer is supposed to fail.
What happens is that the data is downloaded in the closure but then everything just reverts back to its default values as if the download had never happened!
I would really like to contain this server chat logic within the class initializer. Any way I can safely achieve this? I've tried a lot of things so far and can't figure it out.
init?(from user: FIRUser, withUserReference ref: FIRDatabaseReference){
let userID = user.uid
var init_succeeded = false
//These values don't matter. If the init fails
//It'll return an empty class.
//Yes this is a hack lol
self.incognito = false
self.email = "NO"
self.username = "NOPE"
self.ref = ref
self.fir_user = user
self.mute_all = false
//Getting the information from the database
ref.child(userID).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
let value = snapshot.value as? NSDictionary
//Unpacking user preferences
self.incognito = (value?["incognito"] as? Bool)!
self.mute_all = (value?["mute_all"] as? Bool)!
self.email = (value?["email"] as? String)!
self.username = (value?["username"] as? String)!
init_succeeded = true
}) { (error) in
print("ERROR : \(error.localizedDescription)")
}
if !init_succeeded { return nil }
}
Thanks! - Keenan

Answer 1

Simple answer: No
You simply shouldn't return a value from a function when it's dependent on async statements.
This method will always return nil since init_succeeded is most likely set to true after the method returns. Remember, Firebase queries are asynchronous, so once you call observeSingleEvent, the function doesn't wait for that statement to finish executing, it just runs it asynchronously and goes on with the rest of your code (which is the return in this case).
A completion closure is the closest you can get (but your code won't be exactly contained in the initializer that way):
init(from user: FIRUser, withUserReference ref: FIRDatabaseReference, completion: #escaping (Bool) -> Void){
let userID = user.uid
// default values
self.incognito = false
self.email = "NO"
self.username = "NOPE"
self.ref = ref
self.fir_user = user
self.mute_all = false
//Getting the information from the database
ref.child(userID).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
let value = snapshot.value as? NSDictionary
//Unpacking user preferences
self.incognito = (value?["incognito"] as? Bool)!
self.mute_all = (value?["mute_all"] as? Bool)!
self.email = (value?["email"] as? String)!
self.username = (value?["username"] as? String)!
completion(true) // true = success
}) { (error) in
completion(false) // false = failed
print("ERROR : \(error.localizedDescription)")
}
}
And now basically use it like this
let myObject = myClass(from: someUser, withUserReference: someRef, completion: { success in
if success {
// initialization succeeded
}
else {
// initialization failed
}
})
I would suggest though to not retrieve the data in the initializer generally. Perhaps write another function specifically for retrieving the data and only set the default values in init()