Index out of range error while using picker view

Question

I populated a picker view with different arrays, depending on which textfield you click on. However, whenever I choose the fifth row of the "Untergrund" Array the app crashes with the index out of range error. It shows me that row int = 4 and component int = 0. The error occurs in the line where the first if statement is set in the did select row function. I have no idea why this is happening ...

Here is the relevant code:

@IBOutlet weak var Stadt: UITextField!
@IBOutlet weak var Strasse: UITextField!
@IBOutlet weak var Platzart: UITextField!
@IBOutlet weak var Groesse: UITextField!
@IBOutlet weak var AnzToreKoerbe: UITextField!
@IBOutlet weak var Untergrund: UITextField!

// Variable für die Firebase Database

override func viewDidLoad() {
    super.viewDidLoad()

    Stadt.delegate = self
    Untergrund.delegate = self
    Groesse.delegate = self
    AnzToreKoerbe.delegate = self
    Platzart.delegate = self
    Picker.delegate = self
}

@IBOutlet weak var Picker: UIPickerView!

var currentData = [""]

let UntergrundArray = ["Asphalt", "Kunstrasen Sand", "Kunstrasen Granulat", "Rasen", "Tartan", " "]
let StadtArray = ["Norderstedt", "Hamburg", "Berlin", "München"]
let GroesseArray = [ "2 vs 2", "3 vs 3", "4 vs 4", "5 vs 5"]
let AnzTorKoerbe = ["1", "2", "3", "4"]
let Art = ["Fußball", "Basketball"]

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool{
    if textField.tag == 1{
        currentData = StadtArray
    }else if textField.tag == 2{
        currentData = UntergrundArray
    }else if textField.tag == 3 {
        currentData = GroesseArray
    }else if textField.tag == 4 {
        currentData = AnzTorKoerbe
    }else if textField.tag == 5 {
        currentData = Art

    }

    Picker.reloadAllComponents()

    return false;
}

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

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

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

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let itemSelected = currentData[row]

    print(itemSelected)

    if (itemSelected == StadtArray[row]) {
        Stadt.text = StadtArray[row]
    }else if (itemSelected == UntergrundArray[row]) {
        Untergrund.text = UntergrundArray[row]
    }else if (itemSelected == GroesseArray[row]) {
        Groesse.text = GroesseArray[row]
    }else if (itemSelected == AnzTorKoerbe[row]) {
        AnzToreKoerbe.text = AnzTorKoerbe[row]
    }else {
        Platzart.text = Art[row]
    }
}

Answer 1

currentData can be any one of the other arrays. And row can be for an index larger than some of the arrays. This is the cause of the crash.

The proper solution is to fix how you determine which label to update.

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let itemSelected = currentData[row]

    if currentData === StadtArray {
        Stadt.text = itemSelected
    } else if currentData === UntergrundArray {
        Untergrund.text = itemSelected
    } else ... and the others as needed
}

Though a better option might be to add another property to track the current text field.

var currentField: UITextField?

Then update textFieldShouldBeginEditing:

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool{
    currentField = textField
    if textField.tag == 1 {
        currentData = StadtArray
    } else if textField.tag == 2 {
        currentData = UntergrundArray
    } else if textField.tag == 3 {
        currentData = GroesseArray
    } else if textField.tag == 4 {
        currentData = AnzTorKoerbe
    } else if textField.tag == 5 {
        currentData = Art
    }

    Picker.reloadAllComponents()

    return false;
}

Then update didSelectRow:

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let itemSelected = currentData[row]

    if let currentField = currentField {
        currentField.text = itemSelected
    }
}