How to add data to array from Firebase

Question

I try to use Firebase framework and use it in my app, but I have a problem with undestanding, how to retrieving data from firebase and save it in my own array. Firebase structure is very simple and looks like that:

Now my code looks like that:

`var rootRef = Firebase(url: "https://mathgamepio.firebaseio.com/")


var array:[String]?
var count: Int = 0

override func viewDidLoad() {
    super.viewDidLoad()



    rootRef.observeEventType(.ChildAdded) { (snap: FDataSnapshot!) -> Void in


        self.count++
        let math = snap.value["math"] as! String
        print(self.count)
        print(math)


        self.array?.append(math)
        print(self.array)
        print("--------")

    }`

The result of this operation looks like that:

self.array.append doesn't work and is nil always. How to add this data to my own array?

Community · Accepted Answer · 2017-05-23 12:15:32Z

It looks like your array is never initialized, so self.array? will always skip append.

One solution is to check of the array exists:

if (self.array?.append(math)) == nil {
    self.array = [math]
}

There are probably more ways to solve this, but I modified the answer from this question: Adding elements to optional arrays in Swift

Update

Even easier is to simply create the array, before using it:

var array:[String]?
var count: Int = 0

override func viewDidLoad() {
    super.viewDidLoad()

    self.array = [];

    rootRef.observeEventType(.ChildAdded) { (snap: FDataSnapshot!) -> Void in


        self.count++
        let math = snap.value["math"] as! String
        print(self.count)
        print(math)

        self.array?.append(math)
        print(self.array)
        print("--------")

    }
}

Or simply not mark the array as optional:

var array:[String] = []
var count: Int = 0

override func viewDidLoad() {
    super.viewDidLoad()

    rootRef.observeEventType(.ChildAdded) { (snap: FDataSnapshot!) -> Void in

        self.count++
        let math = snap.value["math"] as! String
        print(self.count)
        print(math)

        self.array.append(math)
        print(self.array)
        print("--------")

    }
}

TIL I learned some basic Swift syntax. :-)

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