Downloading too many items in table view from Firebase - ios

Question

When I post from a different device, the tableview I on the current device keeps the items that were previously there and then downloads the items again including the new post, can anyone help me to make it so that it only displays one of each item?
I think the issue is in my downloadFromFirebase().
Here is my code:
class DisplayVC: UIViewController, UITableViewDelegate, UITableViewDataSource, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
#IBOutlet weak var captionField: RoundTextField!
#IBOutlet weak var tableView: UITableView!
#IBOutlet weak var myMainImg: roundImage!
var imageSelected = false
static var imageCache: NSCache<NSString,UIImage> = NSCache()
var posts = [Post]() // array for the posts
var imagePicker: UIImagePickerController!
#IBAction func addImageTapped(_ sender: Any) {
present(imagePicker, animated: true, completion: nil)
}
#IBAction func logoutPressed(_ sender: Any) {
//remove keychain and sign out of firebase
let keychainResult = KeychainWrapper.standard.removeObject(forKey: KEY_UID)
print("AA: ID removed from keychain: \(keychainResult)")
try! FIRAuth.auth()?.signOut()
performSegue(withIdentifier: "goToSignIn", sender: nil)
}
#IBAction func postBtnTapped(_ sender: Any) {
//does this exist? or is it null? if condition is not true then it is executed
guard let caption = captionField.text, caption != "" else {
let alert = UIAlertController(title: "Bad Caption", message: "Caption must be entered", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .cancel, handler: nil))
self.present(alert, animated: true, completion: nil)
return
}
guard let img = myMainImg.image, imageSelected == true else {
let alert = UIAlertController(title: "Bad Image", message: "Image must be choosen", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .cancel, handler: nil))
self.present(alert, animated: true, completion: nil)
return
}
if let imgData = UIImageJPEGRepresentation(img, 0.2){
let imgUid = NSUUID().uuidString
let metadata = FIRStorageMetadata()
metadata.contentType = "image/jpeg"
DataService.ds.REF_POST_IMAGES.child(imgUid).put(imgData, metadata: metadata, completion: { (metadata, error) in
if error != nil{
print("unable to upload image to Firebase storage")
}else{
print("GREAT SUCESS FOR IMAGE ON STORAGE")
let downloadURL = metadata?.downloadURL()?.absoluteString
if let url = downloadURL{
self.postToFireBase(imageURL: url)
}
}
})
}
}
func postToFireBase(imageURL: String){
let post: Dictionary<String, AnyObject> = ["caption": captionField.text as AnyObject,"imageURL":imageURL as AnyObject, "likes":0 as AnyObject,"userName": userName as AnyObject]
let firebasePost = DataService.ds.REF_POSTS.childByAutoId()
firebasePost.setValue(post)
captionField.text = ""
imageSelected = false
myMainImg.image = UIImage(named: "add-image")
posts.removeAll()
tableView.reloadData()
}
//cannot use the view did load for the guard method!
override func viewDidAppear(_ animated: Bool) {
}
override func viewDidLoad() {
super.viewDidLoad()
self.hideKeyboardWhenTappedAround()
tableView.delegate = self
tableView.dataSource = self
imagePicker = UIImagePickerController()
imagePicker.allowsEditing = true
imagePicker.delegate = self
posts.removeAll()
self.downloadFromFirebase()
}
func downloadFromFirebase(){
//"POSTS" Listener, initialize listener and it will work constantly
DataService.ds.REF_POSTS.observe(.value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot]{
for snap in snapshot{
print("SNAP: \(snap)") // make free objects by parsing the JSON
if let postDict = snap.value as? Dictionary<String, AnyObject>{
let key = snap.key
let post = Post(postKey: key, postData: postDict)
self.posts.append(post) //stick the post in the posts Array
}
}
}
self.tableView.reloadData()
})
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return posts.count //number of total posts
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let post = posts[indexPath.row]
if let cell = tableView.dequeueReusableCell(withIdentifier: "PostCell") as? PostCell{
if let img = DisplayVC.imageCache.object(forKey: post.imageURL as NSString){
cell.configureCell(post: post, image: img)
return cell
}else{
cell.configureCell(post: post, image: nil)
return cell
}
}else{
return PostCell()
}
}
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
if let image = info[UIImagePickerControllerEditedImage] as? UIImage{
myMainImg.image = image
}else{
print("AA: Valid image wasn't selected")
}
imagePicker.dismiss(animated: true, completion: nil)
imageSelected = true
}
func hideKeyboardWhenTappedAround() {
let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(dismissKeyboard))
view.addGestureRecognizer(tap)
}
func dismissKeyboard() {
view.endEditing(true)
}
}

Answer 1

Try this:
Include after
let post = Post(postKey: key, postData: postDict)
the following:
if !posts.contains(post) {
self.post.append(post)
}
Let me know if it works!