UIImagePickerController causes duplicate - ios

Question

I am implementing a social media application using Swift. In the MyProfileViewController, I have used UIImagePickerController to change the current user's profile picture. However, usage of UIImagePickerController causes a duplicate of table view rows even though I handle the table view in viewDidLoad, not in viewWillAppear.
To illustrate, here is my viewDidLoad function.
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
self.automaticallyAdjustsScrollViewInsets = false
ref = Database.database().reference()
storageRef = Storage.storage().reference()
ref.child("users").child((Auth.auth().currentUser?.uid)!).observe(.value, with: {
(snapshot) in
let value = snapshot.value as? NSDictionary
let userId = value?["id"] as! String
let username = value?["username"] as! String
let email = value?["userEmail"] as! String
let profilePictureUrl = value?["profilePicture"] as! String
self.currentUser = User(id: userId, username: username, email: email, profilePicture: profilePictureUrl)
self.tableView.reloadData()
})
ref.child("posts").observe(.childAdded, with: {
(snapshot) in
let value = snapshot.value as? NSDictionary
let id = value?["id"] as! String
let tags = value?["tags"] as! String
let facultyName = value?["faculty"] as! String
let courseName = value?["course"] as! String
let questionTitle = value?["title"] as! String
let questionText = value?["description"] as! String
let dateAndTime = value?["dateAndTime"] as! String
let userID = value?["user-id"] as! String
self.ref.child("users").child(userID).observe(.value, with: {
(snapshot) in
let value = snapshot.value as? NSDictionary
let userId = value?["id"] as! String
let username = value?["username"] as! String
let email = value?["userEmail"] as! String
let profilePictureUrl = value?["profilePicture"] as! String
let post = Post(id: id, tags: tags, facultyName: facultyName, courseName: courseName, questionTitle: questionTitle, questionText: questionText, dateAndTime : dateAndTime, username: username)
if userID == Auth.auth().currentUser?.uid {
self.posts.insert(post, at: 0)
}
self.postDictionary[id] = post
let member = User(id: userId, username: username, email: email, profilePicture: profilePictureUrl)
if post.username == member.username {
self.userDictionary[id] = member
}
self.tableView.reloadData()
})
})
}
And here is my UIImagePickerController function:
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
let indexPath = NSIndexPath(row: 0, section: 0)
let cell = tableView.cellForRow(at: indexPath as IndexPath) as! MyProfileInfoCell!
if let image = info[UIImagePickerControllerOriginalImage] as? UIImage {
selectedImage = image
cell?.profilePicture.contentMode = .scaleAspectFit
cell?.profilePicture.image = image
}
var data = NSData()
data = UIImageJPEGRepresentation((cell?.profilePicture.image!)!, 0.8)! as NSData
let filePath = "\((Auth.auth().currentUser?.uid)!)" // path where you wanted to store img in storage
let metaData = StorageMetadata()
metaData.contentType = "image/jpg"
self.storageRef = Storage.storage().reference()
self.storageRef.child(filePath).putData(data as Data, metadata: metaData) {
(metaData,error) in
if let error = error {
print(error.localizedDescription)
return
} else{
let downloadURL = metaData!.downloadURL()!.absoluteString
self.ref.child("users").child((Auth.auth().currentUser?.uid)!).updateChildValues(["profilePicture" : downloadURL])
}
}
self.dismiss(animated: true, completion: nil)
print(self.posts.count)
}
My table view consists of 2 prototype cells. The first prototype cell is for the profile information, in which changing profile picture is handled. The second prototype cell is for showing the posts posted by that user. The problem occurs here. When I change my profile picture, the posts rows are being duplicated.
Can anyone help me with this?

Answer 1

The observe method adds an observer to "users" on your DB. Every time you changes the "users" on DB the following code is executed and a post is added to tableview:
self.ref.child("users").child(userID).observe(.value, with: {
(snapshot) in
let value = snapshot.value as? NSDictionary
let userId = value?["id"] as! String
let username = value?["username"] as! String
let email = value?["userEmail"] as! String
let profilePictureUrl = value?["profilePicture"] as! String
let post = Post(id: id, tags: tags, facultyName: facultyName, courseName: courseName, questionTitle: questionTitle, questionText: questionText, dateAndTime : dateAndTime, username: username)
if userID == Auth.auth().currentUser?.uid {
self.posts.insert(post, at: 0)
}
self.postDictionary[id] = post
let member = User(id: userId, username: username, email: email, profilePicture: profilePictureUrl)
if post.username == member.username {
self.userDictionary[id] = member
}
self.tableView.reloadData()
})
When you update the profile picture the DB is updated too and the above code is executed. That is why the posts are duplicated. To fix that changes the method from observe to observeSingleEvent. The observeSingleEvent method requests data from DB once.
self.ref.child("users").child(userID).observeSingleEvent(.value, with: {
(snapshot) in
let value = snapshot.value as? NSDictionary
let userId = value?["id"] as! String
let username = value?["username"] as! String
let email = value?["userEmail"] as! String
let profilePictureUrl = value?["profilePicture"] as! String
let post = Post(id: id, tags: tags, facultyName: facultyName, courseName: courseName, questionTitle: questionTitle, questionText: questionText, dateAndTime : dateAndTime, username: username)
if userID == Auth.auth().currentUser?.uid {
self.posts.insert(post, at: 0)
}
self.postDictionary[id] = post
let member = User(id: userId, username: username, email: email, profilePicture: profilePictureUrl)
if post.username == member.username {
self.userDictionary[id] = member
}
self.tableView.reloadData()
})