下标的含糊用法（快速3）

我处理数据的首选方式是

FIRDataSnapshot

ref!.observe(.value, with: { (snapshot) in    for child in snapshot.children {        let msg = child as! FIRDataSnapshot        print("(msg.key): (msg.value!)")        let val = msg.value! as! [String:Any]        print("(val["name"]!): (val["message"]!)")    }})