点击字段时数据未填充到 UIPickerView 中

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情节提要板上的一个元素。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，当我点击季节字段时，屏幕底部会出现一个灰色的选择器，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，这是我从关于将数据填充到选择器视图的教程中获得的，但是该教程在主情节提要板上有一个选择器元素。我能得到一些指导吗？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

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

第一行应改为：

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

Answer 2

您的 ViewController 实现了 UIPickerViewDelegate 和 UIPickerViewDataSource 方法，但您需要将 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 class 通过更改

声明它符合 UIPickerDataSource 协议

class ViewController: UIViewController, UIPickerViewDelegate

到

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource

Answer 3

请记住，您必须将 class 设置为 delegate/datasource 才能符合协议方法。 UITableView、UICollectionView 等也是如此

这里是全部的汇总：

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
    }
    }

点击字段时数据未填充到 UIPickerView 中

Data not populating in UIPickerView when field is tapped

ios

swift

uipickerview