我如何获得所需的数据？

Question

    ref = Database.database().reference()

    let currentUserID = Auth.auth().currentUser?.uid

    let userRef = ref.child("users").child(currentUserID!)

    let userRefQuery = userRef.queryOrdered(byChild: "requests").queryEqual(toValue: "received")

    userRefQuery.observeSingleEvent(of: .value, with: { (snapshot) in

        if (snapshot.value is NSNull) {

            print("no data found")
            return
        }

        print("value:")
        print(snapshot.value)

        print("key:")
        print(snapshot.key)

    })

Firebase Database

如何在“请求”下获取具有“已接收”值的用户的用户ID。因为它也可能被“发送”。目前，我没有收到任何数据！

Answer 1

这就是我的工作方式：

ref = Database.database().reference()

let currentUserID = Auth.auth().currentUser?.uid

refHandle = ref.child("users").child(currentUserID!).observe(.value, with: { (snapshot) in

    print(snapshot)

    if let userDict = snapshot.value as? [String: Any] {

        if let requests = userDict["requests"] as? [String: String] {

            print(requests)

            for request in requests {

                if request.value == "sent" {

                    self.userIDs.append(request.key)
                    print(request.key)

                }

            }

        }


    }

}

Answer 2

对于您删除的问题，而不是：

char temp = s[start]

做

char temp = s[i];