如何查询孩​​子的孩子并将孩子的键/值之一存储到变量中？

Question

我正在尝试在Firebase中获得一个孩子的孩子内部的值，并将该值存储到变量中。我认为我的路径不正确，因为每当我运行我的代码时，Xcode都会运行并命中

 childRef.child(uidArray[incLoop]).observeSingleEvent(of: .value,        
 with: {(snap) in.. but doesn't run the code inside the function.

 uidArray contains the uid of the users. How can I query the user's age?

下面是我在Firebase中的数据结构（我也在使用Geofire）

{
"Users" : {
"9n35bgJUZiYJVhnrcTJ5" : {
  "Age" : 21,
  "Strength" : 150,
  "g" : "9q8yywdq7v",
  "l" : [ 37.785834, -122.406417 ]
},
"bW3mGneMy7DkBbElCXXb" : {
  "Age" : 21,
  "Strength" : 150,
  "UID" : "bW3mGneMy7DkBbElCXXb",
  "g" : "9q8yywdq7v",
  "l" : [ 37.785834, -122.406417 ]
}
},
"firebase-hq" : {
"g" : "7zzzzzzzzz",
"l" : [ 0, 0 ]
  }
}


let childRef = Database.database().reference().child("Users")

childRef.child(uidArray[incLoop]).observeSingleEvent(of: .value,  
with: {(snap) in
                print(snap)
                if let snapDict = snap.value as? [String:AnyObject]{
                    let age = snapDict["Age"] as! Int
                    print(String(age))
                    print("Done with Age")
                }
            })
        }