轻按字段时，数据不会在UIPickerView中填充

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要故事板上的元素。 我正在一个项目中进行练习，以便完成此操作后，可以将代码复制到实际上正在尝试开发的项目中。 到目前为止，我所需要的是，当我点击“季节”字段时，屏幕底部会出现一个灰色选择器，但其中没有数据。 我感觉是因为我尝试填充数据的方式，这是我从将数据填充到选择器视图的教程中获得的，但是该教程在主故事板上有一个picker元素。 我可以对此寻求指导吗？ 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
}
}

Answer 1

您的ViewController实现了UIPickerViewDelegate和UIPickerViewDataSource方法，但是您需要将ViewController设置为UIPickerView的委托和数据源。

将此代码添加到viewDidLoad ：

dataPickerView.delegate = self
dataPickerView.dataSource = self

并让您的ViewController类通过更改来声明它符合UIPickerDataSource协议

class ViewController: UIViewController, UIPickerViewDelegate

至

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource

Answer 2

如果要以编程方式获取数据，则需要再设置一个协议：UIPickerViewDataSource。

第一行应更改为：

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

Answer 3

请记住，为了符合协议方法，必须将类设置为委托/数据源。 UITableView，UICollectionView等也是如此。

这是全部放在一起：

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

    @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
        dataPickerView.delegate = self
        dataPickerView.dataSource = self
        //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
    }
    }