Firebase completion listeners in swift

Question

How do you execute a completion listener for firebase in swift? It says there are completion listers for SetValue and UpdateValue in the docs but there is no example.

Answer 1

The completion of a setValue is handled within the {} block (closure). So once the attempt to setValue is made, the code within that block executes. error will be nil if none and snapshot will be the data that was written.

let ref = self.myRootRef.child("some_path")
    ref.setValue("Hello", withCompletionBlock: { (error, snapshot) in
        if error != nil {
            print("oops, an error")
        } else {
            print("completed")
        }
    })

gives a result of

root_ref
   some_path: Hello

and prints "completed"