点击字段时，不会在UIPickerView中填充数据

Question

我正在尝试学习如何以编程方式将数据填充到UIPickerView中，而不是将选择器作为主故事板上的元素。我正在一个项目中练习，所以当我完成这项工作后，我可以将代码复制到我实际尝试开发的项目中。到目前为止，当我点击季节字段时，屏幕底部会出现灰色选择器，但其中没有数据。我有一种感觉，这是因为我试图填充数据的方式，我从一个关于将数据填充到选择器视图的教程中获得，但是教程在主故事板上有一个选择器元素。我可以就此得到一些指示吗？谢谢。

class ViewController: UIViewController, UIPickerViewDelegate {

@IBOutlet var enterSeason: UITextField!

var dataPickerView = UIPickerView()
var season = ["2013", "2014", "2015"] //multi-season
//var season = ["2015"] //single-season

override func viewDidLoad() {
    super.viewDidLoad()

    enterSeason.inputView = dataPickerView
    //enterSeason.inputView = UIPickerView()

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return season.count
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    return season[row] as String
}
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    var itemSelected = season[row] as String
    self.enterSeason.text  = itemSelected
}
}