如何根据 Swift 中另一个选择器视图的选择来填充选择器视图？

Question

寻找一种解决方案来根据同一视图控制器中另一个选择器视图的选择来填充选择器视图。第一个选择一个类别。第二个是该类别的项目。

这是我（Swift 初学者）想出的：

import UIKit

class ViewController: UIViewController, UIPickerViewDataSource,      UIPickerViewDelegate {

var countryClasses = ["US", "EU", "JP"]
var usItems = ["usitem1", "usitem2", "usitem3", "usitem4", "usitem5"]
var euItems = ["euitem1", "euitem2", "euitem3", "euitem4", "euitem5"]
var jpItems = ["jpitem1", "jpitem2", "jpitem3", "jpitem4", "jpitem5"]

@IBOutlet weak var countryPicker: UIPickerView!

@IBOutlet weak var itemPicker: UIPickerView!

override func viewDidLoad() {
    super.viewDidLoad()
    self.countryPicker.dataSource = self;
    self.countryPicker.delegate = self;
    self.itemPicker.dataSource = self;
    self.itemPicker.delegate = self;
}

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

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

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

}

Answer 1

将每个选择器视图与标签相关联（以便可以识别它们），然后在选择器委托中根据这些标识符识别这些选择器并显示另一个

Answer 2

由于两个选择器都使用相同的委托，因此当您的委托方法运行时，您将需要一种方法来识别它们运行，而且您当前的数组结构意味着您将需要一种方法来 select 每个项目数组当国家 selected.

为 selected 项目数组创建一个商店。

var selectedItemsArray = []

向您的委托方法添加一些检查。

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

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    if pickerView == countryPicker {
        return countryClasses.count
    } else if pickerView == itemPicker {
        return selectedItemsArray.count
    }
    return 0
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    if pickerView == countryPicker {
        return countryClasses[row]
    } else if pickerView == itemPicker {
        return selectedItemsArray[row]
    }
    return 0
}

然后您需要执行 Select 行来设置项目存储并重新加载数据。

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == countryPicker {
        switch row {
        case 0:
            selectedItemsArray = usItems
        case 1:
            selectedItemsArray = euItems
        case 2:
            selectedItemsArray = jpItems
        default:
            selectedItemsArray = []  
        }
        // IMPORTANT reload the data on the item picker
        itemPicker.reloadAllComponents()
    } else if pickerView == itemPicker {
        // Get the current item
        var item = selectedItemsArray[row]
        // Assign value to a label based on which array we are using
        if selectedItemsArray == usItems {
            usLabel.text = item
        } else if selectedItemsArray == euItems {
            euLabel.text = item
        } else if selectedItemsArray == jpItems {
            jpLabel.text = item
        }
    }
}

我没有测试过这段代码，但逻辑应该是正确的。

Answer 3

谢谢@Wez！

在 Swift 2.2 中，小而重要的更正 return 作为 String 的函数使其运行良好。

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    if pickerView == countryPicker {
        return countryClasses[row]
    } else if pickerView == itemPicker {
        return selectedItemsArray[row]
    }

    return selectedItemsArray[row] as? String
}

如何根据 Swift 中另一个选择器视图的选择来填充选择器视图？

How can I populate a picker view depending on the selection of another picker view in Swift?

uipickerview

ios

swift