问题与查询Firebase - Swift

我目前正在尝试执行查询以获取显示关注者/关注列表的信息。我目前得到一个错误这样：Could not cast value of type 'FIRDataSnapshot' (0x108967580) to 'NSArray' (0x10b3e3e28).我是新来的火力和仍在学习的查询，我的查询如下：问题与查询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") 

       } 


      }) 

     }

错误的路线是这样的：

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

我树也如下：

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

我试图存储FollowAutoChild信息

我的整个查询功能代码如下：

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") 

       } 


      }) 

      } 

     }

来源

2017-09-01 AndrewS

的误差出现，因为你是铸造** **第一'snapshot.children'的元素，它只是一个元素（在这种情况下是一个'FIRDataSnapshot'），作为'FIRDataSnapshot'的数组。既可以将所有对象作为“FIRDatasnapShot”的数组进行投射，也可以将第一个对象作为FIRDataSnapshot进行投射，但不能同时投射。 – Eric

非常感谢！我不知道！ – AndrewS

很高兴能有帮助:) – Eric

的误差出现，因为你是铸造的snapshot.children的第一元件，这仅仅是一个元件（在这种情况下的FIRDataSnapshot），作为阵列FIRDataSnapshot的。或者将所有对象作为FIRDatasnapShot的数组，或作为FIRDataSnapshot的第一个数组投射，但不能同时投射。

来源

2017-09-01 15:20:04 Eric

你for_in循环应该是这样的

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() 

       }

你做错了铸造

来源

2017-09-01 15:22:39

问题与查询Firebase - Swift

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