如何在IOS中根据用户偏好检索具体的firebase数据结果？

import Firebase

FirebaseApp.configure()

let database = Database.database().reference()

let preference = "偏好值" // 用户的偏好值
let query = database.child("users").queryOrdered(byChild: "preference").queryEqual(toValue: preference)

query.observe(.value) { (snapshot) in
    // 处理查询结果
    for child in snapshot.children {
        if let snapshot = child as? DataSnapshot {
            let userData = snapshot.value as? [String: Any]
            // 处理userData，即符合用户偏好的数据
        }
    }
}