Issue with a query Firebase - Swift - ios

Question

I am currently trying to do a query to obtain the information for displaying a list of followers/following. I am currently getting an error as such: Could not cast value of type 'FIRDataSnapshot' (0x108967580) to 'NSArray' (0x10b3e3e28). I am new to firebase and still learning about queries, my query is as follows:
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")
}
})
}
The line of error is as such:
for s in snapshot.children.allObjects.first as! [FIRDataSnapshot] {
my tree is also as follows:
-Users
---UserUID
-----Followers
--------FollowAutoChild
----------------userFollow
----------------userFollowKey
I am trying to store the FollowAutoChild information
My whole query function code is as follows:
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")
}
})
}
}

Answer 1

The error is appearing because you are casting the first element of snapshot.children, which is just one element(An FIRDataSnapshot in this case), as an array of FIRDataSnapshot's. Either cast all the objects as an array of FIRDatasnapShot's, or the first one as an FIRDataSnapshot but not both at the same time.

Answer 2

Your for_in loop should look like this
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()
}
you are doing wrong casting