[Swift] Get key as well as value in Realtime database

db

{
  "people": {
    "-MPRm-8iCWsKK6B_nuHA": {
      "age": 30,
      "mail": "[email protected]",
      "name": "taro"
    },
  }
}

swift

let ref = Database.database().reference().child("people")

ref.observe(DataEventType.value) { (snapshot) in
    for child in snapshot.children {
        let snap = child as! DataSnapshot
        let key = snap.key    
        let value = snap.value

        // key : -MPRm-8iCWsKK6B_nuHA
        // value : Optional({ age = 30; mail = "[email protected]"; name = taro; })
    }
}