为什么我的代码在完成块中运行两次

Question

我有一些连接到 firebase 的代码，当它到达代码的某个部分时，它会运行两次它也不会删除我的 waitAlertController 它导致我的代码崩溃，因为它运行了两次然后第二次没有值，因为它第一次运行时将其删除，这是我的代码

这是我添加等待视图控制器并启动完成方法的表格视图。

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let alertController = UIAlertController(title: "Accept Bet", message: "Match the bet of " + amountBets[indexPath.row], preferredStyle: .alert)

    let okButton = UIAlertAction(title: "No", style: .default, handler: { (action) -> Void in
        print("Ok button tapped")
    })

    let yesButton = UIAlertAction(title: "Yes", style: .default, handler: { (action) -> Void in
        // let them know to wait a second or the bet won't go through
        var waitController = UIAlertController(title: "Please Wait", message: "Your bet is being processed", preferredStyle: .alert)

        self.present(waitController, animated: true, completion: nil)
        //take away the usersMoney
        self.takeAwayMoney(self.amountBets[indexPath.row],index: indexPath.row, completion: { (result: Bool?) in

            guard let boolResult = result else {
                return
            }
            var getResult = ""
            print("You have taken away the users money")

                print("you made it this far almost there")
                //let delayInSeconds = 3.0 // 1
                //DispatchQueue.main.asyncAfter(deadline: .now() + delayInSeconds) { // 2
        })
        if (self.userHasMoney == true) {
        self.updateBet(indexPath.row, completion: { (result: Bool?) in

            guard let checkRes = result else {
                return
            }


        })

        self.getOpoosingUserNames(self.userName, indexPath.row, completion: { (anothaResult: Bool?) in

            guard let value = anothaResult else {
                return print("didn't work")
            }
                    //wait for the first view to load in case it uploads to fast
                    sleep(1)
                    self.dismiss(animated: true, completion: nil)
                    let successController = UIAlertController(title: "Success", message: "You have made a bet with " + self.opposingUserNames!, preferredStyle: .alert)
                    let okButt = UIAlertAction(title: "Ok", style: .default, handler: nil)
                    successController.addAction(okButt)
                    self.present(successController, animated: true, completion: nil)
                    //lastly delete the opposing UserName
                    self.amountBets.remove(at: indexPath.row)
                    self.tableView.reloadData()
                    print("Second")

        })
        } else {
            //display a alert that lets the user know hes broke
            let brokeController = UIAlertController(title: "Failed", message: "Reason: You don't have enough money!", preferredStyle: .alert)
            let okButt = UIAlertAction(title: "Ok", style: .default, handler: nil)
            brokeController.addAction(okButt)
            self.present(brokeController, animated: true, completion: nil)
        }

    return
    })

    alertController.addAction(okButton)
    alertController.addAction(yesButton)
    present(alertController, animated: true, completion: nil)
}

这是我的 takeMoneyAway 方法

func takeAwayMoney(_ howMuch: String, index: Int, completion: @escaping (Bool)-> ()) -> Void{
        if let notMuch = Int(howMuch) {

            let userID = FIRAuth.auth()?.currentUser?.uid

            datRef.child("User").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
                // Get user value
                let value = snapshot.value as? NSDictionary
                let money = value?["money"] as? String ?? ""

                //convert money to int
                if let conMoney = Int(money) {
                    var conMoreMoney = conMoney
                    if conMoreMoney < notMuch {
                        print(" You don't have enough money")
                        completion(false)
                        return
                    } else {
                        conMoreMoney -= notMuch
                        let values = ["money": String(conMoreMoney)]

                        //update the users money
                        self.datRef.child("User").child(userID!).updateChildValues(values)
                        completion(true)
                        /*
                        self.updateBet(index, completion: { (result: Bool?) in
                            guard let checkResult = result else {
                                return print("Failed to get result")
                            }
                            if checkResult == true {
                                completion(true)
                            } else {
                                completion(false)
                            }
                        })
 */

                    }

                }
                // ...
            }) { (error) in
                print(error.localizedDescription)
            }
        }
    }

我的最后一个方法是去我的数据库更新值并抓住他们下注的人。

 func updateBet(_ index: Int, completion: @escaping (_ something: Bool?) -> Void) {
        let userID = FIRAuth.auth()?.currentUser?.uid
        datRef.child("User").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
            // Get user value
            let value = snapshot.value as? NSDictionary
            // ...


            self.datRef.child("Bets").observe(.childAdded, with: { snapshot in
                //
                // this is the unique identifier of the bet.  eg, -Kfx81GvUxoHpmmMwJ9P
                guard let dict = snapshot.value as? [String: AnyHashable] else {
                    print("failed to get dictionary from Bets.\(self.userName)")
                    return
                }
                let values = ["OpposingUsername": self.userName,"Show": "no"]


                self.datRef.child("Bets").child(self.tieBetToUser[index]).updateChildValues(values)
                let checkTheCodeWentHere = "Success"
                // now get the opposing username which is just the Username registered to that specific bet

                self.datRef.child("Bets").child(self.tieBetToUser[index]).observeSingleEvent(of: .value, with: { snapshot in
                    let thisValue = snapshot.value as? NSDictionary
                    if let username = thisValue?["Username"] as? String {
                        self.opposingUserNames = username
                        completion(true)
                    } else {
                        completion(false)
                    }

                })

            })

        }) { (error) in
            print(error.localizedDescription)
        }


    }

所以在 tableview 方法中有一段代码说 if checkRes == true {} 花括号中的所有代码都运行了两次我用断点检查了这个，有人能告诉我这是为什么吗？

Answer 1

无法实际运行代码并对其进行测试，并且仅基于您上面的 cmets，我相信您所说的部分是这样的：

//take away the usersMoney
self.takeAwayMoney(self.amountBets[indexPath.row],index: indexPath.row, completion:{(result) in
    if result {
        // User has money
    } else {
        // User does not have money
    }
    var getResult = ""
    print("You have taken away the users money")

        print("you made it this far almost there")
        //let delayInSeconds = 3.0 // 1
        //DispatchQueue.main.asyncAfter(deadline: .now() + delayInSeconds) { // 2
})

takeAwayMoney 方法通过闭包的result 参数返回用户是否有钱，并且该参数在方法定义中不是可选的。但是，在上面的代码中，由于某种原因，它被声明为可选的。我更改了代码以删除那段代码，并添加了一个if 条件，指示在执行takeAwayMoney 后您将如何继续。

基本上，您首先调用takeAwayMoney，等待该方法通过闭包返回其结果，然后查看闭包的结果并进行任何后续处理。因此，看起来您确实需要将 if (self.userHasMoney == true) { 条件中的所有代码移动到 takeAwayMoney 完成闭包中。

希望这是有道理的。如果没有，请随时联系我，我会尽力澄清。