Posts Being Uploaded Randomly in Collection View - Swift & Firebase - swift

Question

I have been refactoring my code and now I'm having trouble with the posts.
Whenever I add a new post to the collection view, it is being added in a random cell and out of order, instead of in the first post.
I know the reason is the fetchuser function and from what I'm being told due to the asynchronous loading, but don't know what to do in order to correct this.
Could someone help me figure out what to do so that my posts are added in the first cell?
#objc func observePostsAdoption() {
let postsRef = Database.database().reference().child("posts")
postsRef.queryOrdered(byChild: "postType").queryEqual(toValue: "adopt").observe(.value) { (snapshot) in
var tempPost = [Posts]()
for child in snapshot.children {
if let childSnapshot = child as? DataSnapshot {
let dict = childSnapshot.value as? [String: Any]
let newAdoptiondPost = Posts.transformPost(dict: dict!)
//This will look up all users at once
self.fetchUser(userid: newAdoptiondPost.userid!, completed: {
tempPost.insert(newAdoptiondPost, at: 0)
DispatchQueue.main.async {
self.postsadoption = tempPost
self.adoptionCollectionView.reloadData()
self.refresherAdoption.endRefreshing()
}
})
}
}
}
}
func fetchUser(userid: String, completed: #escaping ()-> Void ) {
Database.database().reference().child("users").child(userid).observeSingleEvent(of: .value) { (snapshot) in
if let dict = snapshot.value as? [String: Any] {
let user = UserProfile.transformUser(dict: dict)
self.users.insert(user, at: 0)
completed()
}
}
}
Here's my Post Struct
class Posts {
//UserView
var uid: String?
var author: UserProfile?
var timestamp: Date?
var userid: String?
func getDateFormattedString() -> String {
let formatter = DateFormatter()
formatter.dateFormat = "MMM d, HH:mm"
return formatter.string(from: self.timestamp!)
}
//Image
var photoUrl: URL?
//PostInformation View
var city: String?
var municipality: String?
var name: String?
var breed : String?
var phone : String?
var address : String?
var petType: String?
var genderType: String?
var comments: String?
}
extension Posts {
static func transformPost(dict: [String: Any]) -> Posts {
let post = Posts()
//Post Picture
let photoUrl = dict["photoUrl"] as? String
post.photoUrl = URL(string: photoUrl!)
//INFO POSTS
post.userid = dict["userid"] as? String
post.city = dict["city"] as? String
post.municipality = dict["municipality"] as? String
post.name = dict["name"] as? String
post.breed = dict["breed"] as? String
post.phone = dict["phone"] as? String
post.address = dict["address"] as? String
post.comments = dict["comments"] as? String
post.petType = dict["petType"] as? String
post.genderType = dict["gender"] as? String
let timestamp = dict["timestamp"] as? Double
post.timestamp = Date(timeIntervalSince1970: timestamp!/1000)
return post
}
}

Answer 1

If you already have the posts ordered by post type you can just do sorting depending on the timestamp. For example
#objc func observePostsAdoption() {
let postsRef = Database.database().reference().child("posts")
postsRef.queryOrdered(byChild: "postType").queryEqual(toValue: "adopt").observe(.value) { (snapshot) in
var tempPost = [Posts]()
for child in snapshot.children {
if let childSnapshot = child as? DataSnapshot {
let dict = childSnapshot.value as? [String: Any]
let newAdoptiondPost = Posts.transformPost(dict: dict!)
//This will look up all users at once
self.fetchUser(userid: newAdoptiondPost.userid!, completed: {
tempPost.insert(newAdoptiondPost, at: 0)
DispatchQueue.main.async {
self.postsadoption = tempPost
self.postsadoption.sort { (p1, p2) -> Bool in
return p1.timeStamp?.compare(p2.timeStamp!) == .orderdDescending
}
self.adoptionCollectionView.reloadData()
self.refresherAdoption.endRefreshing()
}
})
}
}
}
}
With that the posts adoption array will be sorted depending on the timestamp that you have.