picker view array row is will only display 0

Question

I have a picker view of int in my Swift code. It has numbers 1-7 in an array called numbers. When I ask to print numbers[row] inside the didSelectRow function it prints the correct numbers. But within my submit tapped function it only prints 0. It did this in viewWillAppear as well.

I essentially want the row to be a variable that I can use as an int to delay some code.

let numbers = [1,2,3,4,5,6,7]
var days = Int()

override func viewDidLoad() {
    super.viewDidLoad()

    self.pickerView.delegate = self
    self.pickerView.dataSource = self
}

override func viewWillAppear(_ animated: Bool) {
    print(days)
}

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return String(numbers[row])
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return numbers.count
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    var days = numbers[row]
    print(days)
}

@IBAction func submitTapped(_ sender: Any) {
    databaseRef.child("numbers").child(self.TextField.text!).setValue(["thename" : UserDefaults.standard.value(forKey: "nametext")])
    print(days)
    DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(days) , execute: {
        databaseRef.child("numbers/\(self.TextField.text!)").removeValue()
    })

Does anyone know why it is always returning zero in the submit tapped function?

Answer 1

You're initializing days using the Int() constructor, which is always 0. Thus, in your viewWillAppear(_:) method later, 0 is printed out, because that's what days was initialized to be. However, in your pickerView(_:didSelectRow:inComponent:) method, you're using the var keyword to create a new variable called days that is local to the pickerView(_:didSelectRow:inComponent:) method, and the global days variable is never changed, and is always equal to 0. Therefore, later on in your submitTapped(_:) method, the global days is still 0.

I'm going to assume you want to set the global days variable in your pickerView(_:didSelectRow:inComponent:) method to numbers[row]. To do so, you must remove the var keyword next to days inside the pickerView(_:didSelectRow:inComponent:). Inside that method, you can reference it either as days or self.days, as long as you don't use the var or let keyword to redeclare days inside that method

Answer 2

Simply replace

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    var days = numbers[row]
    print(days)

with

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    days = numbers[row]
    print(days)

Your code doesn't work because you are creating new variable and you are not referencing your instance variable.