How to load datas not in realtime in firebase? - swift

Question

I have the following problem to solve:
All datas are loaded in realtime (this time even multiple times per post), but I just want to refresh with a refresher I already have.
This is my refresher:
// Refresher
func refresh() {
refresher = UIRefreshControl()
refresher.attributedTitle = NSAttributedString(string: "Aktualisieren")
refresher.addTarget(self, action: #selector(DiscoveryViewController.refreshData) , for: UIControl.Event.valueChanged)
tableView.addSubview(refresher)
}
#objc func refreshData(sender: Any) {
loadTopPosts()
refresher.endRefreshing()
}
And with this I load all posts:
func loadTopPosts() {
ProgressHUD.show("Lade...", interaction: false)
self.postArray.removeAll()
self.tableView.reloadData()
// Aktuelle Location des aktuell eingeloggten Users laden
guard let currentUserUid = UserApi.shared.CURRENT_USER_ID else { return }
let databaseRef = LocationApi.shared.geoRef
databaseRef.getLocationForKey(currentUserUid) { (location, error) in
if error != nil {
ProgressHUD.showError("Posts konnten nicht geladen werden")
} else if location != nil {
print("Location for \(currentUserUid) is [\(location!.coordinate.latitude), \(location!.coordinate.longitude)]")
// Alle Posts im vorgegebenen Umkreis laden
let REF_GEO_POSTS = Database.database().reference().child("geolocation_posts")
let geoRef = GeoFire(firebaseRef: REF_GEO_POSTS)
// Lade den aktuell eingestellten Radius aus der Datenbank
self.observeRadius(completion: { (radius) in
let currentRadius = radius
// Üperprüfe, welche Posts im Umkreis erstellt wurden
let circleQuery = geoRef.query(at: location!, withRadius: Double(currentRadius)!)
circleQuery.observe(.keyEntered, with: { (postIds, location) in
self.observePost(withPostId: postIds, completion: { (posts) in
guard let userUid = posts.uid else { return }
self.observeUser(uid: userUid, completion: { (users) in
let postArray = UserPostModel(post: posts, user: users)
self.postArray.append(postArray)
self.postArray.sort(by: {$0.post!.secondsFrom1970! > $1.post!.secondsFrom1970!})
self.tableView.reloadData()
self.tableView.setContentOffset(CGPoint.zero, animated: true)
ProgressHUD.dismiss()
})
})
})
})
if self.postArray.count == 0 {
ProgressHUD.dismiss()
}
} else {
ProgressHUD.showError("Posts konnten nicht geladen werden")
}
}
}
Here are the functions where I over serve datas from firebase:
let REF_POSTS = Database.database().reference().child("posts")
func observePost(withPostId id: String, completion: #escaping (PostModel) -> Void) {
REF_POSTS.child(id).observeSingleEvent(of: .value) { (snapshot) in
guard let dic = snapshot.value as? [String: Any] else { return }
let newPost = PostModel(dictionary: dic, key: snapshot.key)
completion(newPost)
}
}
let REF_USERS = Database.database().reference().child("users")
func observeUser(uid: String, completion: #escaping (UserModel) -> Void) {
REF_USERS.child(uid).observeSingleEvent(of: .value) { (snapshot) in
guard let dic = snapshot.value as? [String: Any] else { return }
let newUser = UserModel(dictionary: dic)
completion(newUser)
}
}
func observeRadius(completion: #escaping (String) -> Void) {
guard let currentUserUid = UserApi.shared.CURRENT_USER_ID else { return }
let REF_RADIUS = Database.database().reference().child("users").child(currentUserUid).child("radius")
REF_RADIUS.observeSingleEvent(of: .value) { (radius) in
let currentRadius = radius.value as? String
completion(currentRadius!)
}
}
What I now want to do is to disable the realtime function (updating the tableView only if I refresh). So if I refresh, everything will be displayed correctly.
How to solve this problem?
Thanks in advance for your help!

Answer 1

There is observe, that keeps notifying every time an update happens in the database. And there is observeSingleEvent, that will only provide you data when requested.
https://firebase.google.com/docs/database/ios/read-and-write
And also, your geofire reference will keep notifying you for every update, if you don't want it to do that, remove it like this:
"If you're not interested in getting updates on new/moving users after the initial query, this is also a great moment to remove your observer by calling removeObserverWithFirebaseHandle or removeAllObservers."
in your case it's posts, and that was mentioned here:
https://stackoverflow.com/a/50722984/8869493