tableview duplicating data on back button - arrays

Question

I am creating individual members in my app, and everything works well. I validate user input, store it in a local array, and then pass the data on to Firebase when I tap 'next'. The app takes me from Step 2 to Step 3. So far so good.
This is what Step 2 looks like if I load the app from scratch: Step 2 Existing Users. The users are pulled from Firebase, and everything is correct.
If I add a new user, everything updates fine. I tap the 'next' button, and Firebase updates with 3 users, all with correct data, and I'm taken to Step 3. All is good still.
But if I tap the 'back' button in the upper left corner of Step 3 (provided by my navigation controller), the app takes me back to Step 2 and now a duplicate entry of the new user shows up in my tableview. Somehow a duplicate user is appended to my array. This only shows up AFTER I click the 'back' button. It doesn't show up in Firebase, but I don't know where it's coming from. I've spent all day trying to figure this out. I'm sure it's a simple problem that I'm overlooking, but I could really use the community's help on this one.
I've looked at this but it didn't help me. I did some tests where I printed out users.count and found that on ViewDidLoad, the count was 0, but on the unwind segue, the count updated to 3 when I added a new user (this was correct, because there were 3 users). But then when I went to Step 3 and tapped the 'back' button to get back to Step 2, Step 2's ViewDidLoad showed a users.count of 4. I have no idea why. I'm completely stumped.
Here is my Step 2 View Controller code in its entirety:
class Step2VC: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var usersTableView: UITableView!
var users = [User]() // create variable called 'users' which is an array of type User (which is a class we created)
var firebaseUser: FIRUser!
var firebaseStorage: FIRStorage!
var ref: FIRDatabaseReference!
var cellStyleForEditing: UITableViewCellEditingStyle = .none
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.title = "users"
usersTableView.dataSource = self
usersTableView.delegate = self
usersTableView.tableFooterView = UIView()
// --------
// Firebase
// --------
firebaseUser = FIRAuth.auth()?.currentUser
firebaseStorage = FIRStorage.storage()
ref = FIRDatabase.database().reference().child("users").child(firebaseUser.uid)
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "edit", style: .plain, target: self, action: #selector(editButtonTapped))
loadExistingUsers() // check to see if there are existing users, and if so, load them into tableview
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
usersTableView.reloadData()
}
// ----------
// Table View
// ----------
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return users.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "CustomCell", for: indexPath) as! Step2Cell
cell.myLabel.text = users[indexPath.row].firstName
cell.userImage.image = users[indexPath.row].photo
return cell
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
deleteUserConfirmationAlert(tableViewIndexPath: indexPath)
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
performSegue(withIdentifier: "EditUser", sender: users[indexPath.row])
}
// ----------
// Navigation
// ----------
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "EditUser" {
let nextContoller = segue.destination as! Step2UsersVC
// 'sender' is retrieved from 'didSelectRow' function above
nextContoller.user = sender as? User
nextContoller.navBarTitle = "edit user"
} else if segue.identifier == "AddUser" {
let nextController = segue.destination as! Step2UsersVC
nextController.navBarTitle = "add user"
} else {
print("Segue Initiated:",segue.identifier!)
}
}
#IBAction func unwindToStep2VC(sender: UIStoryboardSegue) {
let sourceVC = sender.source as! Step2UsersVC
let updatedUser = sourceVC.user
if let selectedIndexPath = usersTableView.indexPathForSelectedRow {
// Update an existing user
users[selectedIndexPath.row] = updatedUser!
usersTableView.reloadData()
} else {
// Add a new user
let newIndexPath = IndexPath(row: users.count, section: 0)
users.append(updatedUser!)
usersTableView.insertRows(at: [newIndexPath], with: .automatic)
users.sort(by: {$0.birthday < $1.birthday})
usersTableView.reloadData()
}
}
#IBAction func nextButtonTapped(_ sender: UIButton) {
// check for at least two users
if users.count < 2 {
createAlert(alertTitle: "Users", alertMessage: "You have not created enough users. Please enter in at least two users.")
} else {
// check for at least one parent
if numberOfParents() < 1 {
createAlert(alertTitle: "Users", alertMessage: "You must have at least one parent. Please enter in a parent.")
} else {
confirmationAlert()
}
}
}
// ---------
// Functions
// ---------
// if users exist on Firebase, load them
func loadExistingUsers() {
ref.child("members").observe(.childAdded) { (snapshot: FIRDataSnapshot) in
if let dict = snapshot.value as? [String : Any] {
let userPhotoUrl = dict["profileImageUrl"] as! String
let userFirstName = dict["firstName"] as! String
let userBirthday = dict["birthday"] as! Int
let userPasscode = dict["passcode"] as! Int
let userGender = dict["gender"] as! String
let isUserChildOrParent = dict["childParent"] as! String
let storageRef = FIRStorage.storage().reference(forURL: userPhotoUrl)
storageRef.data(withMaxSize: 1 * 1024 * 1024, completion: { (data, error) in
let pic = UIImage(data: data!)
let user = User(profilePhoto: pic!,
userFirstName: userFirstName,
userBirthday: userBirthday,
userPasscode: userPasscode,
userGender: userGender,
isUserChildOrParent: isUserChildOrParent)
self.users.append(user)
self.users.sort(by: {$0.birthday < $1.birthday})
self.usersTableView.reloadData()
})
}
}
}
func saveUsersToFirebase() {
for user in users {
let storageRef = FIRStorage.storage().reference().child("users").child(firebaseUser.uid).child("members").child(user.firstName)
let profileImg = user.photo
let imageData = UIImageJPEGRepresentation(profileImg, 0.1) // compress photos
storageRef.put(imageData!, metadata: nil, completion: { (metadata, error) in
if error != nil {
return
}
// get Firebase image location and return the URL as a string
let profileImageUrl = (metadata?.downloadURL()?.absoluteString)!
// save user data to Firebase
self.ref?.child("members").child(user.firstName).setValue(["profileImageUrl" : profileImageUrl,
"firstName" : user.firstName,
"birthday" : user.birthday,
"passcode" : user.passcode,
"gender" : user.gender,
"childParent" : user.childParent])
})
}
}
func editButtonTapped() {
if cellStyleForEditing == .none {
cellStyleForEditing = .delete
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "done", style: .done, target: self, action: #selector(editButtonTapped))
} else {
cellStyleForEditing = .none
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "edit", style: .plain, target: self, action: #selector(editButtonTapped))
}
usersTableView.setEditing(cellStyleForEditing != .none, animated: true)
}
func deleteUserConfirmationAlert(tableViewIndexPath: IndexPath) {
// create alert for user to confirm user deletion
let alert = UIAlertController(title: "Delete User", message: "Are you sure you want to delete \(users[tableViewIndexPath.row].firstName)? This cannot be undone.", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "okay", style: .default, handler: { (action) in
alert.dismiss(animated: true, completion: nil)
// remove user from Firebase
self.ref.child("members").child(self.users[tableViewIndexPath.row].firstName).removeValue()
self.users.remove(at: tableViewIndexPath.row)
self.usersTableView.deleteRows(at: [tableViewIndexPath], with: .fade)
}))
alert.addAction(UIAlertAction(title: "cancel", style: .cancel, handler: { (action) in
alert.dismiss(animated: true, completion: nil)
self.usersTableView.reloadData()
}))
present(alert, animated: true, completion: nil)
}
func numberOfParents() -> Int {
var parentCount = 0
for user in users {
if user.childParent == "parent" {
parentCount += 1
}
}
return parentCount
}
func createAlert(alertTitle: String, alertMessage: String) {
let alert = UIAlertController(title: alertTitle, message: alertMessage, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "okay", style: .cancel, handler: { (action) in
alert.dismiss(animated: true, completion: nil)
}))
present(alert, animated: true, completion: nil)
}
func confirmationAlert() {
let alert = UIAlertController(title: "Users", message: "You have entered in \(users.count) users. Are you finished adding family members?", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "continue", style: .default, handler: { (action) in
self.saveUsersToFirebase()
self.performSegue(withIdentifier: "GoToStep3", sender: self)
alert.dismiss(animated: true, completion: nil)
}))
alert.addAction(UIAlertAction(title: "cancel", style: .cancel, handler: { (action) in
alert.dismiss(animated: true, completion: nil)
}))
present(alert, animated: true, completion: nil)
}
}