I've been trying to load in an array of team names that I want to put up on different table view cells, but it never seems to load them properly.
I've been trying to cause the program to wait until it gets values back, but it never seems to get any, since it always crashes, gets a loading error, or just freezes.
var ref: FIRDatabaseReference?
var teamData = [String]()
var teamCount : Int?
var hasfilled = false
var firstRun = false
var currentUser = FIRAuth.auth()?.currentUser
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
ref = FIRDatabase.database().reference()
//Load each team
let path = ref?.child("Users").child(currentUser!.uid).child("joinedTeams")
path?.observeSingleEvent(of: .value, with: { (snapshot) in
let enumerator = snapshot.children
while let rest = enumerator.nextObject() as? FIRDataSnapshot{
let teamName = rest.value as? String
if let teamNameData = teamName {
self.teamData.append(teamNameData)
}
}
self.teamCount = Int(snapshot.childrenCount)
})
if runTillCompletion() == true {
self.tableView.reloadData()
}
}
func runTillCompletion() -> Bool{
if self.teamCount == self.teamData.count {
return true
}
return runTillCompletion()
}
I've tried this several different ways, from a while loop to just reloading it a ton.
I want to reload the view so that it runs the table view methods that determine the number of cells/content of cells.
I'm certain that there a better way to do this, since using a while loop/the recursion function have been painfully messy.
Thanks so much!
Your runTillCompletion method is called earlier before the response from Firebase and hence the tableview is empty. You need to reload the table after fetching data from firebase.
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
ref = FIRDatabase.database().reference()
//Load each team
let path = ref?.child("Users").child(currentUser!.uid).child("joinedTeams")
path?.observeSingleEvent(of: .value, with: { (snapshot) in
let enumerator = snapshot.children
while let rest = enumerator.nextObject() as? FIRDataSnapshot{
let teamName = rest.value as? String
if let teamNameData = teamName {
self.teamData.append(teamNameData)
}
}
self.teamCount = Int(snapshot.childrenCount)
self.tableView.reloadData()
})
}
FIRDatabase.database().reference(withPath: "users/\(currentUser!.uid)/joinedTeams")
.observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshots = snapshot.children.allObjects as? [FIRDataSnapshot] {
self.teamData = snapshots.flatMap { $0.value as? String }
self.tableView.reloadData()
}
}
)
Related
I have two functions that successfully retrieve integers from Firebase. I'd like a third function that does some simple subtraction from the integers gathered in the first two functions.
However, I'm very new to this, so can't get it to work correctly.
The output of the two functions that gather data from Firebase are:
let pointsRedeemedAsInt:Int = Int(Points_Redeem)!
and
let sumOfPointsCompleted = self.challengeList.reduce(0) {$0 + $1.Points}
What I'd like is a third function that looks like this:
let pointsBalance = sumOfPointsCompleted - pointsRedeemedAsInt
However, the third function doesn't recognise sumOfPointsCompleted, nor pointsRedeemedAsInt.
// First Function:
func loadPointsRedeemed() {
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
databaseReference.child("Users").child(userID!).observe(DataEventType.value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
// let Points_Earn = value?["Points_Earned"] as? String ?? ""
let Points_Redeem = value?["Points_Redeemed"] as? String ?? ""
// self.Points_Earned.text = Points_Earn
self.Points_Redeemed.text = Points_Redeem
let pointsRedeemedAsInt:Int = Int(Points_Redeem)!
// Do any additional setup after loading the view.
}
)}
//Second Function:
func LoadPointsCompleted() {
self.challengeList.removeAll()
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let refChallenges = Database.database().reference(withPath: "Challenges").child(userID!).queryOrdered(byChild: "Status").queryEqual(toValue: "Complete")
refChallenges.observeSingleEvent(of: .value, with: { (snapshot) in
//if the reference have some values
if snapshot.childrenCount > 0 {
//clearing the list
self.challengeList.removeAll()
//iterating through all the values
for Challenges in snapshot.children.allObjects as! [DataSnapshot] {
//getting values
let challengeObject = Challenges.value as? [String: AnyObject]
let Points = challengeObject?["Points"] as! Int
//creating challenge object with model and fetched values
let challenge = pointsModel(Points: (Points as Int?)!)
//appending it to list
self.challengeList.append(challenge)
let sumOfPointsCompleted = self.challengeList.reduce(0) {$0 + $1.Points}
let sumOfPointsCompletedString = String(sumOfPointsCompleted)
self.Calc_Earned.text = sumOfPointsCompletedString
}
}
}
)}
// Third Function (which does not work):
func BalanceOfPoints(){
let balance = sum - pointsRedeemedAsInt
}
The error is:
Use of unresolved identifiers sum and pointsRedeemedAsInt
Furthermore, how do I ensure that everything is executed in the right order? ie, the loadPointsCompleted function must run (and complete) first, followed by the loadPointsRedeemed function, and finally the BalanceOfPoints function.
Actually, the problem is that you are not considering that retrieving data from remote sources is asynchronous.
This means that you have to wait for data to be retrieved before calling the other functions.
To achieve this result, you should use swift closure (callback in other languages) with completion handler. Check this documentation.
Change your functions this way:
First Function
func loadPointsRedeemed(completion: #escaping (_:Int)->()){
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
databaseReference.child("Users").child(userID!).observe(DataEventType.value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
// let Points_Earn = value?["Points_Earned"] as? String ?? ""
let Points_Redeem = value?["Points_Redeemed"] as? String ?? ""
// self.Points_Earned.text = Points_Earn
self.Points_Redeemed.text = Points_Redeem
let pointsRedeemedAsInt:Int = Int(Points_Redeem)!
// Do any additional setup after loading the view.
//Call your return back function called "completion"
completion(pointsRedeemedAsInt)
}
)}
Second Function
func loadPointsCompleted(completion: #escaping (_:Int)->()){
self.challengeList.removeAll()
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let refChallenges = Database.database().reference(withPath: "Challenges").child(userID!).queryOrdered(byChild: "Status").queryEqual(toValue: "Complete")
refChallenges.observeSingleEvent(of: .value, with: { (snapshot) in
//if the reference have some values
if snapshot.childrenCount > 0 {
//clearing the list
self.challengeList.removeAll()
//iterating through all the values
for Challenges in snapshot.children.allObjects as! [DataSnapshot] {
//getting values
let challengeObject = Challenges.value as? [String: AnyObject]
let Points = challengeObject?["Points"] as! Int
//creating challenge object with model and fetched values
let challenge = pointsModel(Points: (Points as Int?)!)
//appending it to list
self.challengeList.append(challenge)
}
let sumOfPointsCompleted = self.challengeList.reduce(0) {$0 + $1.Points}
let sumOfPointsCompletedString = String(sumOfPointsCompleted)
self.Calc_Earned.text = sumOfPointsCompletedString
completion(sumOfPointsCompleted)
}
}
)}
Third Function
func balanceOfPoints(completion: #escaping (_:Int)->()) {
loadPointsCompleted{(sum) in
//HERE YOU CAN USE THE RESULT OF loadPointsCompleted
//I CALLED IT sum
loadPointsRedeemed{ (pointsRedeemedAsInt) in
// HERE YOU CAN USE THE RESULT OF loadPointsRedeemed
//I CALLED IT pointsRedeemedAsInt
let balance = sum - pointsRedeemedAsInt
completion(balance)
}
}
}
To call the balance function wherever you want:
balanceOfPoints{ (balance) in
// Whatever you want with balance
}
If you change the view ( for example you set some label text ), be sure to use the functions in the main thread.
The problem is that you are trying to access variables outside the scope of BalanceOfPoints().
Try returning the values you want to use in the equation from the first two functions, loadPointsRedeemed() and LoadPointsCompleted(). This can be done like so:
First Function
func loadPointsRedeemed() -> Int {
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
databaseReference.child("Users").child(userID!).observe(DataEventType.value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
// let Points_Earn = value?["Points_Earned"] as? String ?? ""
let Points_Redeem = value?["Points_Redeemed"] as? String ?? ""
// self.Points_Earned.text = Points_Earn
self.Points_Redeemed.text = Points_Redeem
let pointsRedeemedAsInt:Int = Int(Points_Redeem)!
// Do any additional setup after loading the view.
return pointsRedeemedAsInt
}
)}
Second Function
func loadPointsCompleted() -> Int {
self.challengeList.removeAll()
databaseReference = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let refChallenges = Database.database().reference(withPath: "Challenges").child(userID!).queryOrdered(byChild: "Status").queryEqual(toValue: "Complete")
refChallenges.observeSingleEvent(of: .value, with: { (snapshot) in
//if the reference have some values
if snapshot.childrenCount > 0 {
//clearing the list
self.challengeList.removeAll()
//iterating through all the values
for Challenges in snapshot.children.allObjects as! [DataSnapshot] {
//getting values
let challengeObject = Challenges.value as? [String: AnyObject]
let Points = challengeObject?["Points"] as! Int
//creating challenge object with model and fetched values
let challenge = pointsModel(Points: (Points as Int?)!)
//appending it to list
self.challengeList.append(challenge)
}
let sumOfPointsCompleted = self.challengeList.reduce(0) {$0 + $1.Points}
let sumOfPointsCompletedString = String(sumOfPointsCompleted)
self.Calc_Earned.text = sumOfPointsCompletedString
return sumOfPointsCompleted
}
}
)}
Third Function
func balanceOfPoints() -> Int {
let sum = loadPointsCompleted()
let pointsRedeemedAsInt = loadPointsRedeemed()
let balance = sum - pointsRedeemedAsInt
return balance
}
Now, wherever you call the functions loadPointsRedeemed() and loadPointsCompleted(), replace these calls with balanceOfPoints.
Notice the main changes I made to your code are adding return values to your functions so they can be used in other areas of your code. Check out the Swift Functions Documentation to learn more.
I am working with the following Firebase Database:
I add new chatIDs with the following code:
DatabaseReference.users(uid: self.uid).reference().child("chatIds/\(chat.uid)").setValue(chat.uid)
I need to add a single child to the individual "chatIDs" that is a random string that I will generate but I haven't worked with Firebase for that long so I am not sure how to do add children this far in. How can I write the code to do this?
Based on your database structure, a possible implementation of you want would be:
let ref = Database.database().reference()
// Generating the chat id
let refChats = ref.child("chats")
let refChat = refChats.childByAutoId()
// Accessing the "chatIds branch" from a user based on
// his id
let currentUserId = self.uid
let refUsers = ref.child("users")
let refUser = refUsers.child(currentUserId)
let refUserChatIds = refUser.child("chatIds")
// Setting the new Chat Id key created before
// on the "chatIds branch"
let chatIdKey = refChat.key
let refUserChatId = refUserChatIds.child(chatIdKey)
refUserChatIds.setValue(chatIdKey)
I think what you're looking for is this
let key = firebaseRef.child("users").child("\(String(describing: uid))").child("chatIds").childByAutoId().key
let timestamp = Int(Date().timeIntervalSince1970)
let child = ["key":key,
"name": name as String,
"date": birth as String,
"created": "\(timestamp)"]
firebaseRef.child("users").child("\(String(describing: uid!))").child("chatIds").child(key).setValue(child)
as example I'm saving the key, name, date, and created, as Childs of chatIds, with the childByAutoId, that generates you a random key, so you can locate it when searching the object.
import UIKit
import Firebase
class ChatListVC: UIViewController {
var ref: FIRDatabaseReference!
var messages: [FIRDataSnapshot]! = []
fileprivate var _refHandle: FIRDatabaseHandle?
override func viewDidLoad() {
super.viewDidLoad()
self.userDetail()
}
func userDetail(){
_refHandle = self.ref.child("users").child("child id").observe(.value, with: { [weak self] (snapshot) -> Void in
guard let strongSelf = self else { return }
guard let dict = snapshot.value as? [String:Any] else { return }
//access data from dict
let MyName = dict["MyName"] as? String ?? ""
})
}
I've been struggling with this all day, it doesn't seem to make any sense because I have very similar code that is working fine. I've tried everything, I've tried making a separate method that returns a string array, but none of it has worked. Every time, the postIDs array is set to null when accessed outside of the bracket followed by the parentheses (after the line reading "print(self.postIDs)"). Thanks for any help you could give me.
var postIDs = [String]()
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.delegate = self
let ref = Database.database().reference()
let uid = Auth.auth().currentUser!.uid
ref.child("users").child(uid).child("saved").observeSingleEvent(of: .value, with: { snapshot in
var ids = [String]()
let saved = snapshot.value as! [String:AnyObject]
for (elem, _) in saved {
ids.append(elem)
}
self.postIDs = ids
print(self.postIDs) // returns the values I would expect
})
ref.removeAllObservers()
guard self.postIDs.count >= 1 else {return} // postIDs count is equal to 0 here, and when I print postIDs the result is []
It is because
ref.child("users").child(uid).child("saved").observeSingleEvent(of: .value, with: { snapshot in
var ids = [String]()
let saved = snapshot.value as! [String:AnyObject]
for (elem, _) in saved {
ids.append(elem)
}
self.postIDs = ids
print(self.postIDs) // returns the values I would expect
})
works on background and other line of code executes before the callback came
Check the following code
override func viewDidLoad() {
super.viewDidLoad()
usersTableView.dataSource = self
usersTableView.delegate = self
// getSnapShot()
let databaseRef = Database.database().reference()
databaseRef.child("Users").observe(.value, with: { (snapshot) in
if snapshot.exists() {
self.postData = snapshot.value! as! [String : AnyObject]
self.postData.removeValue(forKey: self.appDelegate.KeyValue)
// self.getUserNames(Snapshot: self.postData)
}
else{
print("No users")
}
print(self.postData) //Does not return nil
self.getSnapShot() //Take snapshot outside paranthesis
})
print(self.postData) //Returns nil
}
func getSnapShot() {
print(self.postData) //Value of Snapshot is printed
}
I cannot get my firebase data to display in my tableviewcell. I have read through dozens of questions but none seem to have the same set-up and issues.
I have observers set up in the viewDidLoad of the TableViewController :
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
// Setup observers that perform a closure each time a book is added,
// removed, or changed.
func setupDBListeners() {
// returns each book in order by title.
let ref = FIRDatabase.database().reference()
ref.child(K.bookKey)
.queryOrdered(byChild: K.titleKey)
.observe(.childAdded, with: { (snapshot) in
let book = self.convertSnapshotToBookObj(snapshot)
self.books.append(book)
self.tableView.reloadData()
})
// Listen for changes in book data.
ref.child(K.bookKey)
.observe(.childChanged, with: { (snapshot) in
let book = self.convertSnapshotToBookObj(snapshot)
for i in 0...self.books.count {
if self.books[i].id == book.id {
self.books[i] = book
self.tableView.reloadData()
return
} }
})
// Listen for books removed.
ref.child(K.bookKey)
.observe(.childRemoved, with: { (snapshot) in
let book = self.convertSnapshotToBookObj(snapshot)
for i in 0...self.books.count {
if self.books[i].id == book.id {
self.books.remove(at: i)
self.tableView.reloadData()
return
} }
}) }
}
And then outside of that I have a function to convert that to an object of the array:
func convertSnapshotToBookObj(_ snap: FIRDataSnapshot) -> Book {
let bookValues = snap.value as! [String : AnyObject]
let id = snap.key
let author = bookValues[K.authorKey] == nil ? "" : bookValues[K.authorKey]! as! String
let title = bookValues[K.titleKey] == nil ? "" : bookValues[K.titleKey]!
as! String
let year = bookValues[K.yearKey] == nil ? "" : bookValues[K.yearKey]! as!
String
// Return a book object with the properties set.
let book = Book()
book.id = id
book.author = author
book.title = title
book.year = year
self.tableView.reloadData()
return book
}
func generateDataForRecents() {
if URLArrayStringThisSeason.count == 0 {
self.activityIndicator2.isHidden = false
self.activityIndicator2.startAnimating()
}
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("palettes").queryLimited(toFirst: 100).observe(.value, with: { (snapshot) in
if let snapDict = snapshot.value as? [String:AnyObject]{
for each in snapDict as [String:AnyObject]{
let URL = each.value["URL"] as! String
self.URLArrayStringRecents.append(URL)
//print(self.URLArrayString.count)
//print(snapshot)
//let pictureTitle = each.value["title"] as! String
print(self.URLArrayStringRecents.count)
}
}
self.whatsNewCollectionView?.reloadData() //Reloads data after the number and all the URLs are fetched
self.activityIndicator2.stopAnimating()
self.activityIndicator2.isHidden = true
})
}
The following code does a retrieval of data each time the function is called, or when a new data is added.
This is extremely useful when the app is first started up or closed and then restarted. However, when the app is running, whenever a new entry is added, the code seemed to run again and thus appending twice the amount of new data.
For example, when there are already 15 entries identified and then suddenly a new entry is added, the array of the URL would contain 15+16 thus amounting to a total of 31.
How do I make it such that the new data is added to the array instead of adding the entire snapshot in?
You do that by listening for .childAdded events, instead of listening for .value:
var query = databaseRef.child("palettes").queryLimited(toFirst: 100)
query.observe(.childAdded, with: { (snapshot) in
let URL = snapshot.childSnapshot(forPath/: "URL").value as! String
self.URLArrayStringRecents.append(URL)
}
Since you have a limit-query, adding a 101st item means that one item will be removed from the view. So you'll want to handle .childRemoved too:
query.observe(.childRemoved, with: { (snapshot) in
// TODO: remove the item from snapshot.key from the araay
})
I recommend that you spend some time in the relevant documentation on handling child events before continuing.
Please check below method. I have use this method not getting any duplicate entry.
func getallNotes()
{
let firebaseNotesString: String = Firebase_notes.URL
let firebaseNotes = FIRDatabase.database().referenceFromURL(firebaseNotesString).child(email)
firebaseNotes.observeEventType(.Value, withBlock: { snapshot in
if snapshot.childSnapshotForPath("Category").hasChildren()
{
let child = snapshot.children
self.arrNotes = NSMutableArray()
self.arrDictKeys = NSMutableArray()
for itemsz in child
{
let childz = itemsz as! FIRDataSnapshot
let AcqChildKey : String = childz.key
if AcqChildKey == AcqIdGlobal
{
if (childz.hasChildren() == true)
{
let dictChild = childz.value as! NSMutableDictionary
self.arrDictKeys = NSMutableArray(array: dictChild.allKeys)
for i in 0..<self.arrDictKeys.count
{
let _key = self.arrDictKeys.objectAtIndex(i).description()
print(_key)
let dictData : NSMutableDictionary = NSMutableDictionary(dictionary: (dictChild.valueForKey(_key)?.mutableCopy())! as! [NSObject : AnyObject])
dictData.setObject(_key, forKey: "notesId")
self.arrNotes.addObject(dictData)
}
}
}
}
self.tableviewNote.reloadData()
}
})
}
As for the query for removed child,
query.observe(.childRemoved, with: { (snapshot) in
print(snapshot)
let URL = snapshot.childSnapshot(forPath: "URL").value as! String
self.URLArrayStringThisSeason = self.URLArrayStringThisSeason.filter() {$0 != URL}
self.thisSeasonCollectionView.reloadData()
})
it will obtain the URL of the removed child and then update the array accordingly.