Swift如何删除图的数据集

Question

我正在使用图表（danielgindi /图表） 当我点击按钮时，当我单击（addDataSet）时，chartView将显示数据集，-<可以 但是当我点击两次（removeDataSet）不起作用时。 chartView仍显示旧数据集并添加新的数据集。

var tapped: Bool = false
let chartDataSet1 = LineChartDataSet()    
let chartData = LineChartData()

@IBAction func firstBtn(_ sender: Any) {

    var dataEntries1 = [ChartDataEntry]()
    for i in 0..<100 {
        let y = arc4random()%60
        let entry = ChartDataEntry.init(x: Double(i), y: Double(y))
        dataEntries1.append(entry)
    }
    let chartDataSet1 = LineChartDataSet(entries: dataEntries1, label: nil)
    chartDataSet1.colors = [.black]


    if tapped{
        chartView.data?.removeDataSet(chartDataSet1)
        chartView.data?.notifyDataChanged()
        chartView.notifyDataSetChanged()
        tapped = false

    }else {
        chartView.data?.notifyDataChanged()
        chartView.notifyDataSetChanged()
        chartView.data?.addDataSet(chartDataSet1)

        tapped = true
    }
}
viewDidLoad
let chartData = LineChartData(dataSets: [chartDataSet1]
chartView.data = chartData