UIPICKERVIEWER DELEGATE-FUNKTION
class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

let staedte = ["Brüssel", "Mailand", "Moskau", "Kairo", "Paris", "Rom"]
@IBOutlet var pickerview: UIPickerView!


override func viewDidLoad() {
  super.viewDidLoad()
  pickerview.delegate=self
  pickerview.dataSource = self
} 

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

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

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

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
  // selected Index
} 

Plausibilität mit zwei Werten
uiPickerViewer mit zwei Spalten