在 Swift 中，如何在进行有效选择时更改具有多个组件的 UIPickerView 中文本的背景颜色

Question

下面的代码会将 UIPickerView 的背景颜色更改为青色，表明当总行索引 = 6 时它是一个有效的选择。希望在视图（已选择）中使用 pickerLabel 背景以在所有四个组件中变为青色选择有效时。有什么想法吗？

import UIKit

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    @IBOutlet weak var myPicker: UIPickerView!
    let pickerData0 = ["0R","1R","2R","3R","4R","5R","6R"]
    let pickerData1 = ["0B","1B","2B","3B","4B","5B","6B"]
    let pickerData2 = ["0Y","1Y","2Y","3Y","4Y","5Y","6Y"]
    let pickerData3 = ["0G","1G","2G","3G","4G","5G","6G"]

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        myPicker.dataSource = self
        myPicker.delegate = self

    }

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


    //Mark: Delegates and data sources
    //Mark: Data Sources
    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
        return 4
    }

    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return pickerData0.count
    }
    //Mark: Delegates

    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        let redIndex = myPicker.selectedRowInComponent(0)
        let blueIndex = myPicker.selectedRowInComponent(1)
        let yellowIndex = myPicker.selectedRowInComponent(2)
        let greenIndex = myPicker.selectedRowInComponent(3)

        if redIndex + blueIndex + yellowIndex + greenIndex == 6 {
            myPicker.backgroundColor = UIColor.cyanColor()
        } else {
            myPicker.backgroundColor = UIColor.whiteColor()
        }   
    }


    func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView!) -> UIView {

        switch component {
        case 0:
            var pickerLabel = view as! UILabel!
            if view == nil {
                pickerLabel = UILabel()
                pickerLabel.textColor = UIColor.redColor()
                pickerLabel.backgroundColor = UIColor.grayColor()
                pickerLabel.textAlignment = NSTextAlignment.Center
                pickerLabel.text = pickerData0[row]
                pickerLabel.font = UIFont(name: "Georgia", size: 26)
            }
            return pickerLabel
        case 1:
            var pickerLabel = view as! UILabel!
            if view == nil {
                pickerLabel = UILabel()
                pickerLabel.textColor = UIColor.blueColor()
                pickerLabel.backgroundColor = UIColor.grayColor()
                pickerLabel.textAlignment = NSTextAlignment.Center
                pickerLabel.text = pickerData1[row]
                pickerLabel.font = UIFont(name: "Georgia", size: 26)
            }
            return pickerLabel
        case 2:
            var pickerLabel = view as! UILabel!
            if view == nil {
                pickerLabel = UILabel()
                pickerLabel.textColor = UIColor.yellowColor()
                pickerLabel.backgroundColor = UIColor.grayColor()
                pickerLabel.textAlignment = NSTextAlignment.Center
                pickerLabel.text = pickerData2[row]
                pickerLabel.font = UIFont(name: "Georgia", size: 26)
            }
            return pickerLabel
        case 3:
            var pickerLabel = view as! UILabel!
            if view == nil {
                pickerLabel = UILabel()
                pickerLabel.textColor = UIColor.greenColor()
                pickerLabel.backgroundColor = UIColor.grayColor()
                pickerLabel.textAlignment = NSTextAlignment.Center
                pickerLabel.text = pickerData3[row]
                pickerLabel.font = UIFont(name: "Georgia", size: 26)
            }
            return pickerLabel
        default:
          return pickerView
        }
    }
}

Answer 1

您希望视图（选中）中的 pickerLabel 背景在所有四个组件中变为青色。您可以更改 pickviewdidSelectRow 中的代码：

if redIndex + blueIndex + yellowIndex + greenIndex == 6 {
        myPicker.backgroundColor = UIColor.cyanColor()
    } else {
        myPicker.backgroundColor = UIColor.whiteColor()
    }

至：

if redIndex + blueIndex + yellowIndex + greenIndex == 6 {
  myPicker.viewForRow(row, forComponent: component)?.backgroundColor = UIColor.cyanColor()
} else {
  myPicker.viewForRow(row, forComponent: component)?.backgroundColor = UIColor.whiteColor()
}

顺便说一句，我不确定是否符合您的需求。

在 Swift 中，如何在进行有效选择时更改具有多个组件的 UIPickerView 中文本的背景颜色

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