点击字段时未在 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，而不是将选取器作为主情节提要上的元素。我正在一个项目中练习，这样当我完成这项工作时，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，当我点击赛季字段时，屏幕底部会出现一个灰色选择器，但其中没有数据。我有一种感觉，这是因为我尝试填充数据的方式，这是我从将数据填充到选取器视图中的教程中获得的，但该教程在主情节提要上有一个选取器元素。我可以得到一些方向吗？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

您的视图控制器实现了UIPickerViewDelegate和UIPickerViewDataSource方法，但您需要将视图控制器设置为UIPickerView的委托和数据源。

将此代码添加到viewDidLoad：

dataPickerView.delegate = self
dataPickerView.dataSource = self

并让你的 ViewController 类通过更改来声明它符合 UIPickerDataSource 协议

class ViewController: UIViewController, UIPickerViewDelegate

自

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，必须将类设置为委托/数据源才能符合协议方法。UITableView，UICollectionView等也是如此。

这是所有内容汇总在一起：

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
    }
    }