Firebase Observe method - sporadic downtime? - ios

Question

I am having random downtimes of connection to firebase using the observeSingleEvent and observe methods in Swift for iOS.
I use multiple ways of connecting to my Firebase database using their REST API.
I use sometimes the method of going through the full URL, like for example,
https://example.firebaseio.com/problems.json.
This always returns data correctly.
When I for example use, observeSingleEvent, that sometimes no code in this gets ran, at all! And that is consistent across view controllers.
The database is still up as using the URL method 100% works, but sometimes using observeSingleEvent it does work, perfectly! But without changing any code, sometimes these events just stop working. I try rebuilding, logging in and out, combination of both, and ive even come to the conclusion that if I leave it for a while, it works again.
Does anyone have any logical reason why the sporadic downtimes occur, and what I can do to fix it? As the code works and i dont change it, but then it stops, for a while across the whole app.
Thanks for your help. Below is an example of code that sometimes runs, and sometimes doesnt.
func getComments() -> Int{
print("getting comments")
let ref = FIRDatabase.database().reference(withPath: "comments")
let query = ref.queryOrdered(byChild: "problem_id").queryEqual(toValue: self.id)
print("Starting observing");
query.observeSingleEvent(of: .value, with: { (snapshot) in
print("Got snapshot");
print(snapshot.childrenCount)
self.commentCount = Int(snapshot.childrenCount)
})
print("returning the comment count");
return commentCount
}

Answer 1

I am fairly new to Firebase, but from my limited experience of observing references, I've learned that observing things takes time to complete, so it is not guaranteed that the code in the closure is executed before what comes next in code. What I would suggest trying (and I'm not positive that it will work) is to modify your code so that it takes a completion handler, guaranteeing that the code in the observing block is completed before getting your result.
So your new code would be
func getComments(completion: #escaping (Int) -> Void) {
print("getting comments")
let ref = FIRDatabase.database().reference(withPath: "comments")
let query = ref.queryOrdered(byChild: "problem_id").queryEqual(toValue: self.id)
print("Starting observing");
query.observeSingleEvent(of: .value, with: { (snapshot) in
print("Got snapshot");
print(snapshot.childrenCount)
print("returning the comment count")
let commentCount = Int(snapshot.childrenCount)
self.commentCount = commentCount
completion(commentCount)
})
}
Then, when you want to use the code, you call it like
getComments(completion: { commentCount in
print(commentCount)
//Do other stuff with comment count
})
It's kinda ugly, but that's the solution that I came up with when I first had similar problems.