Why is my firebase database not waiting to update values - ios

Question

So I am really new to threading and I've been reading up on it all day. For some reason though the data isn't loading before other code executes
Basically I need all the values that have a key ["whatever"] to be filled into an array, which works in other places because I don't need to load it first. So i have checked and double checked the keys that I am updating do exist and the keys I am extracting do exist maybe not the values yet but the keys do.
The problem is the code goes to fast to through the method. How would I make the main thread wait untill my firebase has loaded the data I have tried it below but it does not seem to be working
here is my code
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: "You must wait for the bet to go through", preferredStyle: .alert)
self.present(waitController, animated: true, completion: nil)
//take away that bitches money
self.takeAwayMoney(self.amountBets[indexPath.row], completion: { (result: Bool?) in
guard let boolResult = result else {
return
}
if boolResult == true {
self.updateBet(indexPath.row, completion: {(result: String?) in
guard let resultRecieved = result else {
return
}
print(self.opposingUserNames)
//let delayInSeconds = 7.0 // 1
//DispatchQueue.main.asyncAfter(deadline: .now() + delayInSeconds) { // 2
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
print(self.opposingUserNames)
self.amountBets.remove(at: indexPath.row)
self.tableView.reloadData()
print("Second")
print(self.opposingUserNames)
//}
})
} else {
return
}
})
//then delete that cell and do another pop up that says successful
// check if value is yes or no in the database
})
alertController.addAction(okButton)
alertController.addAction(yesButton)
present(alertController, animated: true, completion: nil)
}
The below function updates the values OpposingUsername and show
func updateBet(_ index: Int, completion: #escaping (_ something: String?) -> 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)
// now get the opposing username which is just the Username registered to that specific bet
self.datRef.child("Bets").child(self.tieBetToUser[index]).observe(.childAdded, with: { snapshot in
guard let dict2 = snapshot.value as? [String: AnyHashable] else {
return
}
let userNameOfOtherPlayer = dict2["Username"] as? String
self.opposingUserNames = userNameOfOtherPlayer!
completion(self.opposingUserNames)
})
})
}) { (error) in
print(error.localizedDescription)
}
}
ok so with this updated code it cuts out the logic errors I had earlier, but now the app hangs on my waitAlertViewController. Not sure why. it does updated the bet in the firebase database so I know its working and running that code but its like never completing it all. sorry bibscy I see what you mean now
completion handlers are pretty powerful once you understand them better

Answer 1

//Notice that I made `result: String?` optional, it may or may not have a value.
func getOpoosingUserNames(_ username: String,_ index: Int, completion: #escaping (_ result: String?) -> 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
let username = value?["username"] as? String ?? ""
self.userName = username
// ...
self.datRef.child("Bets").observe(.childAdded, with: { snapshot in
//
// this is the unique identifier of the bet. eg, -Kfx81GvUxoHpmmMwJ9P
let betId = snapshot.key as String
guard let dict = snapshot.value as? [String: AnyHashable] else {
print("failed to get dictionary from Bets.\(self.userName)")
return
}
if let show = dict["Show"] as? String {
let opposingUser = dict["OpposingUsername"] as? String
self.opposingUserNames.append(opposingUser!)
}
completion(opposingUserNames)
})
}) { (error) in
print(error.localizedDescription)
}
}
//update the be
func updateBet(_ index: Int, completion: #escaping (_ something: [String]?) -> 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"]
//store the values received from Firebase in let valueOfUpdate and pass this
// constant to your completion handler completion(valueOfUpdate) so that you can use this value in func
//tableView(_ tableView:_, didSelectRowAt indexPath:_)
let valueOfUpdate = self.datRef.child("Bets").child(self.tieBetToUser[index]).updateChildValues(values)
completion(valueOfUpdate)
}) { (error) in
print(error.localizedDescription)
}
}
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
//take away that bitches money
self.takeAwayMoney(self.amountBets[indexPath.row])
//then delete that cell and do another pop up that says successful
// check if value is yes or no in the database
self.updateBet(indexPath.row, completion: {(result: String) in
guard let resultReceivedInupdateBet = result, else {
print("result of updateBet() is \(result)")
}
print("If you see this print, database was updated")
//calling this method with the indexPath.row clicked by the user
self.getOpoosingUserNames(self.userName, indexPath.row, completion: { (result: [String]) in
guard let resultReceivedIngetOpoosingUserNames = result{
print("result of getOpoosingUserNames is \(result)")
}
print("If you see this print, you received a value from db after calling getOpoosingUserNames and that value is in \(result) ")
//result is not nil, resultReceivedIngetOpoosingUserNames has the same value as result.
}//end of self.getOpoosingUserNames
self.checkForNo(indexPath.row)
self.amountBets.remove(at: indexPath.row)
self.tableView.reloadData()
print(self.opposingUserNames)
let successController = UIAlertController(title: "Success", message: "You have made a bet with " + self.opposingUserNames[indexPath.row], 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.opposingUserNames.remove(at: indexPath.row)
})
alertController.addAction(okButton)
alertController.addAction(yesButton)
present(alertController, animated: true, completion: nil)
}