Unable to assign values to array outside of function scope. Swift and Firebase

Question

class myChallengesController: UIViewController,UITableViewDelegate, UITableViewDataSource{
   ...
   var myChallenges = [challenge]() //Here i declare an empty array of type challenge
   ...

below is the function i'm using the get all the challenges for a particular user.

func getAllChallenges(){
        var challenges = NSDictionary()
        FIRDatabase.database().reference(withPath: "challenges").observeSingleEvent(of: .value, with: { (snapshot) in
            // getting all of the challenges.

            challenges = (snapshot.value as? NSDictionary)!
            for (_,value) in challenges{
                let test = value as! NSDictionary
                let tempChallenge = challenge()
                for (key,_) in test{
                    // print("key:\(key), value : \(val)")
                    switch(key as! String){

                    case "owner":
                        tempChallenge.owner = test[key] as? String
                        break
                    case "participants":
                        let tempArray = tempChallenge.convertStringToArray(participants: (test[key] as? String)!)
                        tempChallenge.participants = tempArray
                        break
                    case "title":
                        tempChallenge.title = test[key] as? String
                        break
                    case "bounty":
                        tempChallenge.bounty = test[key] as? String
                        break
                    case "details":
                        tempChallenge.details = test[key] as? String
                        break
                    case "location":
                        tempChallenge.location = test[key] as? String
                        break
                    case "subtitle":
                        tempChallenge.subtitle = test[key] as? String
                        break
                    case "duration":
                        tempChallenge.duration = test[key] as? String
                        break
                    case "challengeID":
                        tempChallenge.challengeID = test[key] as? String
                        break
                    default:
                        break
                    }

                }

Here I append each challenge to the myChallenges array. If I test an print data from the first challenge, it works.

                self.myChallenges.append(tempChallenge)
                print("title: \(self.myChallenges[0].title)") -->this works
                print("\(self.myChallenges.count)")
            }
        }) { (error) in
            print(error.localizedDescription)
        }
    }

But when i go and try to access the challenges that were added to the myChallenges array, it appears as if no data was added. Here is where i am accessing the data added to the array.

//this is inside of the tableview cellForRowAt function

cell.jobPosition.text = myChallenges[0].subtitle

cell.timeRemaining.text = myChallenges[0].duration

cell.owner.text = myChallenges[0].owner

when the above code runs i get the "index out range" error

Is it possible that you're trying to read from the array before it has been populated? I assume since that function is asynchronous, the cell will try to initialise itself on first load (before the data comes back). — Samah
– Samah, Commented Jan 21, 2018 at 0:17
That works, Thanks! but if i want to iterate through multiple items in the array, what should I use? indexPath.row wont work — Cesa Salaam
– Cesa Salaam, Commented Jan 21, 2018 at 2:12

Samah · Accepted Answer · 2018-01-21 05:17:51Z

You need to provide the UITableView with an appropriate data source, and optionally a delegate. You'll want to do something like this:

// ViewController.viewDidLoad
tableView.register(MyCell.self, forCellReuseIdentifier: "MyCell")
tableView.dataSource = self

class MyCell: UITableViewCell {
    var jobPosition: UITextField!
    // TODO: configure cell
}

extension ViewController: UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return myChallenges.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as! MyCell
        cell.jobPosition.text = myChallenges[indexPath.row].subtitle
        return cell
    }
}

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