Firebase observeSingleEvent completion handler - ios

Question

I have a FirebaseManager class and a get data function.
When calling this function, I need to get this data in the place from which it is called.
I am trying to do something like
import Firebase
class FirebaseManager {
var ref = Database.database().reference()
func getData (path: String) -> DataSnapshot {
self.ref.child(path).observeSingleEvent(of: .value) { (snapshot) in
if snapshot.exists() {
print(snapshot.value!)
return snapshot // XCODE ERROR - Cannot convert return expression of type 'Void' to return type 'DataSnapshot'
} else {
print("No data by path \(path)")
}
}
}
}

Answer 1

As your title suggests, what you'll need a completion handler. You can pass that in as a parameter to your function. It might look something like this:
func getData(path: String, completion: #escaping (DataSnapshot) -> Void) {
self.ref.child(path).observeSingleEvent(of: .value) { (snapshot) in
if snapshot.exists() {
completion(snapshot)
} else {
print("No data by path \(path)")
}
}
}
Then, you can call it like this:
getData(path: "myPath") { snapshot in
//do something with snapshot here
}
//no access to snapshot here
Note that you have access to snapshot inside the closure (the { }), so you can't access snapshot after the closure.
Personally, I'd probably refactor a bit so that you'd be returning the actual data than you want from inside the snapshot (like a String, a Dictionary, etc) rather than returning the DataSnapshot itself, but that's a matter of preference.