下标使用不明确 (Swift 3)

Question

对于这个 Firebase 数据拉取，我错误地使用了以下代码中的下标，但我无法弄清楚我做错了什么。我收到 let uniqueID = each.value["Unique ID Event Number"] as! Int 行下标使用不明确的错误。

// Log user in
if let user = FIRAuth.auth()?.currentUser {

       let uid = user.uid
       // values for vars sevenDaysAgo and oneDayAgo set here

       ...

       let historyRef = self.ref.child("historyForFeedbackLoop/\(uid)")
            historyRef.queryOrdered(byChild: "Unix Date").queryStarting(atValue: sevenDaysAgo).queryEnding(atValue: oneDayAgo).observeSingleEvent(of: .value, with: { snapshot in

                if (snapshot.value is NSNull) {
                    print("user data not found")
                }
                else {

                    if let snapDict = snapshot.value as? [String:AnyObject] {

                        for each in snapDict {

                            // Save the IDs to array.
                            let uniqueID = each.value["Unique ID Event Number"] as! Int
                            self.arrayOfUserSearchHistoryIDs.append(uniqueID)
                        }

                    }
                    else{
                        print("SnapDict is null")
                    }
                }
       })
}

我尝试应用我从这个中学到的东西，但我无法弄清楚我遗漏了什么，因为我认为我让编译器知道它是什么类型的字典 "as? [String:AnyObject]"

如有任何想法或想法，我们将不胜感激！

Answer 1

我处理数据的首选方式是尽可能晚地解包 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"]!)")
    }
})

Answer 2

考虑到 Frank 的反馈，以下是我使用的实际工作代码，它遵循该方法，以防有用。

// Log user in
if let user = FIRAuth.auth()?.currentUser {

   let uid = user.uid
   // values for vars sevenDaysAgo and oneDayAgo set here

   ...

   let historyRef = self.ref.child("historyForFeedbackLoop/\(uid)")
        historyRef.queryOrdered(byChild: "Unix Date").queryStarting(atValue: sevenDaysAgo).queryEnding(atValue: oneDayAgo).observeSingleEvent(of: .value, with: { snapshot in

            if (snapshot.value is NSNull) {
                print("user data not found")
            }
            else {

                 for child in snapshot.children {

                    let data = child as! FIRDataSnapshot
                    let value = data.value! as! [String:Any]
                    self.arrayOfUserSearchHistoryIDs.append(value["Unique ID Event Number"] as! Int)
                 }
            }
   })
}

下标使用不明确 (Swift 3)

Ambiguous Use of Subscript (Swift 3)

dictionary

subscript

firebase

swift

firebase-realtime-database