How to get a keyname by its nested values in firebase?

Question

My firebase is modeled this way. I want to write a query to get userID(simplelogin:1) where email is "[email protected]".

Here I want to get key: "simplelogin:1" by searching with it's email address:"[email protected]"

I am using firebase SDK for iOS. Can somebody suggest me a query for this? In Javascript or Objective-C

Answer 1

After little messing around I found answer to the question:

Firebase *ref = [_rootReference childByAppendingPath:@"Users"];

[[[ref queryOrderedByChild:@"Email"]queryEqualToValue:@"[email protected]" ]
 observeEventType:FEventTypeChildAdded withBlock:^(FDataSnapshot *snapshot) {
     NSLog(@"%@ Key %@ Value", snapshot.key,snapshot.value);
 }];

There snaphot.key will be the value simplelogin:1 that I wanted.