問題與查詢Firebase - Swift

我目前正在嘗試執行查詢以獲取顯示關注者/關注列表的信息。我目前得到一個錯誤這樣：Could not cast value of type 'FIRDataSnapshot' (0x108967580) to 'NSArray' (0x10b3e3e28).我是新來的火力和仍在學習的查詢，我的查詢如下：問題與查詢Firebase - Swift

if isFollowers == true { 
      self.isFollowers = true 
      ref = ref.child("followers") 
      let query = ref.queryOrdered(byChild: "userFollow") 
      query.queryLimited(toLast: 5).observeSingleEvent(of: .value, with: { (snapshot : FIRDataSnapshot) in 

       if snapshot.childrenCount > 0 { 
        for s in snapshot.children.allObjects.first as! [FIRDataSnapshot] { 
         print("are we even in here?") 
         let item = s.value as! Dictionary<String,AnyObject?> 
         let user = FollowInfoForUser(dictionary: item as Dictionary<String,AnyObject>) 
         self.userFollowIndex.insert(user, at: 0) 
         print(self.userFollowIndex) 
         //print(self.userFollowIndex.count) 
         self.collectionView.reloadData() 

        } 

       } else { 

        print("sorry no followers for you to see") 

       } 


      }) 

     }

錯誤的路線是這樣的：

for s in snapshot.children.allObjects.first as! [FIRDataSnapshot] {

我樹也如下：

-Users 
---UserUID 
-----Followers 
--------FollowAutoChild 
----------------userFollow 
----------------userFollowKey

我試圖存儲FollowAutoChild信息

我的整個查詢功能代碼如下：

func setValues(isFollowers : Bool, isFollowing : Bool, isViewingSelf : Bool, isViewingOther : Bool, key : String) { 

     var ref = FIRDatabase.database().reference().child("users") 

     if isViewingSelf { 
      print("we are viewing us") 
      ref = ref.child(FIRAuth.auth()!.currentUser!.uid) 
     } else 
      if isViewingOther { 
      print("we are viewing them") 
      ref = ref.child(key) 

     } 


     if isFollowers == true { 
      self.isFollowers = true 
      ref = ref.child("followers") 
      let query = ref.queryOrdered(byChild: "userFollow") 
      query.queryLimited(toLast: 5).observeSingleEvent(of: .value, with: { (snapshot : FIRDataSnapshot) in 

       if snapshot.childrenCount > 0 { 
        for s in snapshot.children.allObjects.first as! [FIRDataSnapshot] { 
         print("are we even in here?") 
         let item = s.value as! Dictionary<String,AnyObject?> 
         let user = FollowInfoForUser(dictionary: item as Dictionary<String,AnyObject>) 
         self.userFollowIndex.insert(user, at: 0) 
         print(self.userFollowIndex) 
         //print(self.userFollowIndex.count) 
         self.collectionView.reloadData() 

        } 

       } else { 

        print("sorry no followers for you to see") 

       } 


      }) 

      } 

     }

來源

2017-09-01 AndrewS

的誤差出現，因爲你是鑄造** **第一'snapshot.children'的元素，它只是一個元素（在這種情況下是一個'FIRDataSnapshot'），作爲'FIRDataSnapshot'的數組。既可以將所有對象作爲「FIRDatasnapShot」的數組進行投射，也可以將第一個對象作爲FIRDataSnapshot進行投射，但不能同時投射。 – Eric

非常感謝！我不知道！ – AndrewS

很高興能有幫助:) – Eric

的誤差出現，因爲你是鑄造的snapshot.children的第一元件，這僅僅是一個元件（在這種情況下的FIRDataSnapshot），作爲陣列FIRDataSnapshot的。或者將所有對象作爲FIRDatasnapShot的數組，或作爲FIRDataSnapshot的第一個數組投射，但不能同時投射。

來源

2017-09-01 15:20:04 Eric

你for_in循環應該是這樣的

for s in snapshot.children.allObjects as! [FIRDataSnapshot] { 
        print("are we even in here?") 
        let item = s.value as! [String: AnyObjcet] 
        let user = FollowInfoForUser(dictionary: item) 
        self.userFollowIndex.insert(user, at: 0) 
        print(self.userFollowIndex) 
        //print(self.userFollowIndex.count) 
        self.collectionView.reloadData() 

       }

你做錯了鑄造

來源

2017-09-01 15:22:39

問題與查詢Firebase - Swift

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