我该如何将UISlider与崩溃的图表连接起来？

Question

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我想以最佳方式将UISlider连接到图表，以计算保证金值。我应该怎么做？我遵循了教程，并使用了步进器，但想使用textfield和UISlider进行尝试

我收到此消息：

  

由于未捕获的异常'NSUnknownKeyException'而终止应用程序，原因：'[ setValue：forUndefinedKey：]：此类不适用于键iosStepper的键值编码。'

import UIKit
import Charts

class ViewController: UIViewController {

//    @IBOutlet weak var iosStepper: UIStepper!

    @IBOutlet weak var iosSlidder: UISlider!


//    @IBOutlet weak var macStepper: UIStepper!
//

    @IBOutlet weak var macSlidder: UISlider!

    @IBOutlet weak var pieChart: PieChartView!

    var iosDataEntry = PieChartDataEntry(value: 0)
    var macDataEntry = PieChartDataEntry(value: 0)

    var numberOfDownloadsDataEntries = [PieChartDataEntry]()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        pieChart.chartDescription?.text = ""

        iosDataEntry.value = Double(iosSlidder.value)
        iosDataEntry.label = "iOS"

        macDataEntry.value = Double(macSlidder.value)
        macDataEntry.label = "iOS"

        numberOfDownloadsDataEntries = [iosDataEntry, macDataEntry]
        updateChartData()
    }
    @IBAction func changeiOS(_ sender: UISlider)
    {
        iosDataEntry.value = Double(sender.value)
        updateChartData()

    }
    @IBAction func changeMac(_ sender: UISlider)
    {
        macDataEntry.value = Double(sender.value)
        updateChartData()
    }

    func updateChartData()
    {
        let chartDataSet =  PieChartDataSet(entries: numberOfDownloadsDataEntries , label:nil)
        let charData = PieChartData(dataSet: chartDataSet)
        let colors = [UIColor(named: "iosColor"), UIColor(named: "macColor")]
        chartDataSet.colors = colors as! [NSUIColor]
        pieChart.data = charData
    }

}

  

2019-07-19 21：33：35.806645 + 0200 testchart [49920：24590312] ***由于未捕获的异常'NSUnknownKeyException'而终止应用程序，原因：'[ setValue：forUndefinedKey：]：此类与键iosStepper的键值编码不兼容。'