Swift firebase search is one reload behind - swift

Question

I have a search function in my app which works perfectly except for the fact that it seems to be one reload behind. For example if I type in 'S' nothing will show but if I then type an 'a' after all the results for 'S' will show up. I tried adding collectionView reload at the end of the fetch function but if I do that nothing shows up period.
#objc func textFieldDidChange(_ textField: UITextField) {
guard let text = textField.text else { return }
if text.count == 0 {
self.posts.removeAll()
self.filteredPosts.removeAll()
} else {
fetchSearchedPosts(searchTerm: text)
}
self.collectionView.reloadData()
}
func fetchSearchedPosts(searchTerm: String) {
self.collectionView.refreshControl?.endRefreshing()
let ref = Database.database().reference().child("posts").queryOrdered(byChild: "title").queryStarting(atValue: searchTerm).queryEnding(atValue: "\(searchTerm)\u{f8ff}")
ref.observeSingleEvent(of: .value) { (snapshot) in
if !snapshot.exists() { return }
guard let dictionaries = snapshot.value as? [String: Any] else { return }
self.posts.removeAll()
dictionaries.forEach({ (key, value) in
guard let postDictionary = value as? [String: Any] else { return }
guard let uid = postDictionary["uid"] as? String else { return }
Database.fetchUserWithUID(uid: uid, completion: { (user) in
let post = Post(postId: key, user: user, dictionary: postDictionary)
let nowTimeStamp = Date().timeIntervalSince1970
let dateTime = post.endTimeDate
let timeStamp = dateTime.timeIntervalSince1970
if nowTimeStamp < timeStamp {
post.id = key
self.posts.append(post)
} else {
return
}
})
self.posts.sort(by: { (post1, post2) -> Bool in
return post1.title.compare(post2.title) == .orderedAscending
})
})
self.collectionView.reloadData()
}
}

Answer 1

You need a DispatchGroup as you have nested asynchronous calls
func fetchSearchedPosts(searchTerm: String) {
self.collectionView.refreshControl?.endRefreshing()
let ref = Database.database().reference().child("posts").queryOrdered(byChild: "title").queryStarting(atValue: searchTerm).queryEnding(atValue: "\(searchTerm)\u{f8ff}")
ref.observeSingleEvent(of: .value) { (snapshot) in
if !snapshot.exists() { return }
guard let dictionaries = snapshot.value as? [String: Any] else { return }
self.posts.removeAll()
let g = DispatchGroup() ///// 1
dictionaries.forEach({ (key, value) in
guard let postDictionary = value as? [String: Any] else { return }
guard let uid = postDictionary["uid"] as? String else { return }
g.enter() ///// 2
Database.fetchUserWithUID(uid: uid, completion: { (user) in
let post = Post(postId: key, user: user, dictionary: postDictionary)
let nowTimeStamp = Date().timeIntervalSince1970
let dateTime = post.endTimeDate
let timeStamp = dateTime.timeIntervalSince1970
if nowTimeStamp < timeStamp {
post.id = key
self.posts.append(post)
} else {
g.leave() ///// 3.a
return
}
g.leave() ///// 3.b
})
})
g.notify(queue:.main) { ///// 4
self.posts.sort(by: { (post1, post2) -> Bool in
return post1.title.compare(post2.title) == .orderedAscending
})
self.collectionView.reloadData()
}
}
}