我有一个使用 Firebase 实时数据库的 iOS swift 应用程序。如果我到目前为止正常使用该应用程序，我找不到任何问题。但是，我想预测边缘情况。

我正在尝试在推送更新之前对我的应用程序进行压力测试，而我这样做的一种方法是快速从一个带有 tableView 的 VC 到下一个 VC(一个详细 VC)来回切换。如果我多次这样做，最终 tableview 将显示大量重复数据。

我通过在我的模拟器上打开一个 TableView 并进入我的 Firebase 控制台并手动更改一个值并立即在设备上更改字符串来测试我的应用程序。

所以我很困惑，如果我的 tableview 不断检查值应该是多少，为什么它会显示错误数量的 child 。

// 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()
                }
            })
        }
    })
}

最佳答案

我得到了帮助并彻底更改了我的代码，所以现在它可以工作了

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)
    }

}

关于ios - Firebase 实时阵列计数不匹配，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44379578/