Firebase Realtime Array count mismatch - ios

Question

I have an iOS swift app using Firebase realtime database. If I use the app normally so far I cannot find any issue. However, I want to anticipate edge cases.
I am trying to stress test my app before I push the update, and one way I am doing it is quickly going back and forth from a VC with a tableView to the next VC which is a detail VC. If I do it several times eventually the tableview will show lots of duplicate data.
I have tested my app by having a tableview open on my simulator and going into my Firebase Console and manually changing a value and instantly on the device the string changes.
So I am confused as to why my tableview would show an incorrect amount of children if it is constantly checking what the value should be.
// MARK: Firebase Methods
func checkIfDataExits() {
DispatchQueue.main.async {
self.cardArray.removeAll()
self.ref.observe(DataEventType.value, with: { (snapshot) in
if snapshot.hasChild("cards") {
self.pullAllUsersCards()
} else {
self.tableView.reloadData()
}
})
}
}
func pullAllUsersCards() {
cardArray.removeAll()
let userRef = ref.child("users").child((user?.uid)!).child("cards")
userRef.observe(DataEventType.value, with: { (snapshot) in
for userscard in snapshot.children {
let cardID = (userscard as AnyObject).key as String
let cardRef = self.ref.child("cards").child(cardID)
cardRef.observe(DataEventType.value, with: { (cardSnapShot) in
let cardSnap = cardSnapShot as DataSnapshot
let cardDict = cardSnap.value as! [String: AnyObject]
let cardNickname = cardDict["nickname"]
let cardType = cardDict["type"]
let cardStatus = cardDict["cardStatus"]
self.cardNicknameToTransfer = cardNickname as! String
self.cardtypeToTransfer = cardType as! String
let aCard = CardClass()
aCard.cardID = cardID
aCard.nickname = cardNickname as! String
aCard.type = cardType as! String
aCard.cStatus = cardStatus as! Bool
self.cardArray.append(aCard)
DispatchQueue.main.async {
self.tableView.reloadData()
}
})
}
})
}

Answer 1

I got help and changed my code drastically, so now it works
func checkIfDataExits() {
self.ref.observe(DataEventType.value, with: { (snapshot) in
if snapshot.hasChild("services") {
self.pullCardData()
} else {
DispatchQueue.main.async {
self.collectionView.reloadData()
}
}
})
}
func pullCardData() {
let cardRef = self.ref.child("cards")
cardRef.observe(DataEventType.value, with: { (snapshot) in
for cards in snapshot.children {
let allCardIDs = (cards as AnyObject).key as String
if allCardIDs == self.cardID {
if let childId = self.cardID {
let thisCardLocation = cardRef.child(childId)
thisCardLocation.observe(DataEventType.value, with: { (snapshot) in
let thisCardDetails = snapshot as DataSnapshot
if let cardDict = thisCardDetails.value as? [String: AnyObject] {
self.selectedCard?.cardID = thisCardDetails.key
self.selectedCard?.nickname = cardDict["nickname"] as? String ?? ""
self.selectedCard?.type = cardDict["type"] as? String ?? ""
self.pullServicesForCard()
}
})
}
}
}
})
}
func pullServicesForCard() {
if let theId = self.cardID {
let thisCardServices = self.ref.child("cards").child(theId).child("services")
thisCardServices.observe(DataEventType.value, with: { (serviceSnap) in
if self.serviceArray.count != Int(serviceSnap.childrenCount) {
self.serviceArray.removeAll()
self.fetchAndAddAllServices(serviceSnap: serviceSnap, index: 0, completion: { (success) in
if success {
DispatchQueue.main.async {
self.collectionView.reloadData()
}
}
})
}
})
}
}
func fetchAndAddAllServices(serviceSnap: DataSnapshot, index: Int, completion: #escaping (_ success: Bool) -> Void) {
if serviceSnap.hasChildren() {
if index < serviceSnap.children.allObjects.count {
let serviceChild = serviceSnap.children.allObjects[index]
let serviceID = (serviceChild as AnyObject).key as String
let thisServiceLocationInServiceNode = self.ref.child("services").child(serviceID)
thisServiceLocationInServiceNode.observeSingleEvent(of: DataEventType.value, with: { (thisSnap) in
let serv = thisSnap as DataSnapshot
if let serviceDict = serv.value as? [String: AnyObject] {
let aService = ServiceClass(serviceDict: serviceDict)
self.serviceCurrent = serviceDict["serviceStatus"] as? Bool
self.serviceName = serviceDict["serviceName"] as? String ?? ""
self.serviceURL = serviceDict["serviceURL"] as? String ?? ""
self.serviceFixedBool = serviceDict["serviceFixed"] as? Bool
self.serviceFixedAmount = serviceDict["serviceAmount"] as? String ?? ""
self.attentionInt = serviceDict["attentionInt"] as? Int
self.totalArr.append((serviceDict["serviceAmount"] as? String)!)
// self.doubleArray = self.totalArr.flatMap{ Double($0) }
// let arraySum = self.doubleArray.reduce(0, +)
// self.title = self.selectedCard?.nickname ?? ""
// if let titleName = self.selectedCard?.nickname {
// self.title = "\(titleName): \(arraySum)"
// }
aService.serviceID = serviceID
if serviceDict["serviceStatus"] as? Bool == true {
self.selectedCard?.cStatus = true
} else {
self.selectedCard?.cStatus = false
}
if !self.serviceArray.contains(where: { (service) -> Bool in
return service.serviceID == aService.serviceID
}) {
self.serviceArray.append(aService)
self.serviceArray.sort {$1.serviceAttention < $0.serviceAttention}
}
}
self.fetchAndAddAllServices(serviceSnap: serviceSnap, index: index + 1, completion: completion)
})
}
else {
completion(true)
}
}
else {
completion(false)
}
}