tableView not refreshing - ios

Question

I am new to programming and currently building an app where I collect data from Firebase.
I thought it would be nice to implement this refreshing animation, when the view is pulled down. Now I have the problem that nothing gets refreshed at all (it was working fine in the beginning). Also every time the app launches the tableView is empty at first and when you make the pushdown it reloads, but wrong.
I am really struggling. Can anyone see anything wrong in my code?
class ViewController: BaseViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet var newsfeedTableView: UITableView!
#IBOutlet weak var activityIndicatorView: UIActivityIndicatorView!
private let refreshControl = UIRefreshControl()
var ref: DatabaseReference!
var posts = [String]()
var timeRef = [String]()
var userRef = [String]()
override func viewDidLoad() {
super.viewDidLoad()
addSlideMenuButton()
setupTableView()
ref = Database.database().reference()
ref.child("posts").observe( .childAdded, with: { snapshot in
let newPost = snapshot.value as? NSDictionary
let post_title:String = newPost!["post_title"] as? String ?? "error"
let newPostTime = snapshot.value as? NSDictionary
let post_time:String = newPostTime!["post_time"] as? String ?? "error collecting timestamp"
let newPostUser = snapshot.value as? NSDictionary
let post_user:String = newPostUser!["post_user"] as? String ?? "Team"
self.posts.insert(post_title, at: 0)
self.timeRef.insert(post_time, at: 0)
self.userRef.insert(post_user, at: 0)
self.newsfeedTableView.reloadData()
})
}
private func setupTableView() {
if #available(iOS 10.0, *) {
newsfeedTableView.refreshControl = refreshControl
} else {
newsfeedTableView.addSubview(refreshControl)
}
refreshControl.addTarget(self, action: #selector(refreshNewsFeedTableView(_:)), for: .valueChanged)
}
#objc private func refreshNewsFeedTableView(_ sender: Any) {
//self.refreshControl.beginRefreshing()
self.newsfeedTableView.reloadData()
self.refreshControl.endRefreshing()
self.activityIndicatorView.stopAnimating()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return posts.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! NewsfeedCell
cell.customTextLabel?.text = posts[indexPath.row]
cell.customTimeLabel?.text = timeRef[indexPath.row]
cell.customNameLabel?.text = userRef[indexPath.row]
return cell
}
}
class NewsfeedCell: UITableViewCell {
#IBOutlet weak var customTextLabel: UILabel!
#IBOutlet weak var customNameLabel: UILabel!
#IBOutlet weak var customTimeLabel: UILabel!
}

Answer 1

Here
#objc private func refreshNewsFeedTableView(_ sender: Any)
you don't do any API requests to get the data then reload the table and end refreshing , and since you use observe here
ref.child("posts").observe( .childAdded, with: { snapshot in
then you'll get any new data , if you need to implement the refresh then insert all database code inside a function and replace observe with observeSingleEvent and call it from viewDidLoad and from the refresh selector method
ref.child("posts").observeSingleEvent( .value, with: { snapshot in
Note with the suggested approach you will get all the childs at a time so don't forget to clean the array inside the callback of observeSingleEvent to avoid duplicating values , also consider making one dataSource array instead of 3 here
self.posts.insert(post_title, at: 0)
self.timeRef.insert(post_time, at: 0)
self.userRef.insert(post_user, at: 0)
probably with creating a model
struct Item {
let post:String
let time:String
let user:String
}

Answer 2

Only problem I can see in the code is, you are using .childAdded to observe events from firebase but according to firebase document:
The child_added event is typically used when retrieving a list of
items from the database. Unlike value which returns the entire
contents of the location, child_added is triggered once for each
existing child and then again every time a new child is added to the
specified path. The event callback is passed a snapshot containing the
new child's data. For ordering purposes, it is also passed a second
argument containing the key of the previous child.
So, if you want to receive all the data of any particular node, you need to use value event but not child_added as stated here:
The value event is used to read a static snapshot of the contents
at a given database path, as they existed at the time of the read
event. It is triggered once with the initial data and again every time
the data changes. The event callback is passed a snapshot containing
all data at that location, including child data. In the code example
above, value returned all of the blog posts in your app. Everytime a
new blog post is added, the callback function will return all of the
posts.

Answer 3

Reload UItableView in DispatchQueue.main, try this code.
override func viewDidLoad() {
super.viewDidLoad()
addSlideMenuButton()
setupTableView()
ref = Database.database().reference()
ref.child("posts").observe( .childAdded, with: { snapshot in
let newPost = snapshot.value as? NSDictionary
let post_title:String = newPost!["post_title"] as? String ?? "error"
let newPostTime = snapshot.value as? NSDictionary
let post_time:String = newPostTime!["post_time"] as? String ?? "error collecting timestamp"
let newPostUser = snapshot.value as? NSDictionary
let post_user:String = newPostUser!["post_user"] as? String ?? "Team"
self.posts.insert(post_title, at: 0)
self.timeRef.insert(post_time, at: 0)
self.userRef.insert(post_user, at: 0)
DispatchQueue.main.async() {
self.newsfeedTableView.reloadData()
}
})
}