Swift autocomplete firebase searching - swift

Question

I have created an application where users can search for posts (user-generated) within the app. Recently it has gotten to the point where I can't load all the users at once without it crashing.
The old function would simply load the entire post node and then filter as shown below. Is it possible to replicate something similar to this with a lot more data?
self.posts.filter { (post) -> Bool in
return
post.title.lowercased().contains(searchText.lowercased())
}
I have created a new function from reading the firebase documentation. Which is intended to handle more data.
New function
var users = [User]()
fileprivate func fetchUsers(username: String) {
let ref = Database.database().reference().child("users").queryOrdered(byChild: "username").queryStarting(atValue: username).queryEnding(atValue: "\(username)\\uf8ff")
ref.observeSingleEvent(of: .value) { (snapshot) in
guard let dictionaries = snapshot.value as? [String: Any]
else { return }
dictionaries.forEach({ (key, value) in
if key == Auth.auth().currentUser?.uid {
return
}
guard let userDictionary = value as? [String: Any] else { return }
let user = User(uid: key, dictionary: userDictionary)
self.users.append(user)
})
self.users.sort(by: { (user1, user2) -> Bool in
return user1.username.compare(user2.username) == .orderedAscending
})
self.collectionView?.reloadData()
}
}
Firebase database
"users" : {
"0Udc81ELBJP7UpYiESqPj5gLDx9A" : {
"username" : "First_User"
},
"13ThJZlpkgUCcZ4zaRzzaAHFjat2" : {
"username" : "Test_User"
}
},
This function, however, is lethargic and doesn't autocomplete as it uses to (similar to how Instagram does theirs). You need to type full words into the search bar before anything comes up.
I assume there is a way to have an autocompleted search bar as it's stock standard on most apps these days. Any help fixing this is appreciated.

Answer 1

My guess is that you're calling fetchUsers each time the user changes the text in the search box.
In that case you'll need to clear the previous contents from the list of users whenever fetchUsers runs. So something like:
func fetchUsers(username: String) {
let ref = Database.database().reference().child("users").queryOrdered(byChild: "username").queryStarting(atValue: username).queryEnding(atValue: "\(username)\\uf8ff")
ref.observeSingleEvent(of: .value) { (snapshot) in
guard let dictionaries = snapshot.value as? [String: Any]
else { return }
self.users.removeAll() // clear all previous results
dictionaries.forEach({ (key, value) in
if key == Auth.auth().currentUser?.uid {
return
}
guard let userDictionary = value as? [String: Any] else { return }
let user = User(uid: key, dictionary: userDictionary)
self.users.append(user)
})
self.users.sort(by: { (user1, user2) -> Bool in
return user1.username.compare(user2.username) == .orderedAscending
})
self.collectionView?.reloadData()
}
}