Ios 带valueFormatter的Swift图表模块

我正在使用Swift图表，我的x轴是一个月数组[0,0.5,1.5，…，240]，但我想在x轴上显示的是年，所以我的新x轴是[0.0,1,2,3…，20]；我曾经

lineChartView.xAxis.setLabelsToSkip(23)

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现在，我一直在处理格式化部分，我不知道如何将x数组格式化为整数和整数。以下是我用来绘制图表的内容，我不知道如何使用：

lineChartView.xAxis.valueFormatter?.stringForXValue(Int, original: String, viewPortHandler: lineChartView.viewPortHandler)

我尝试使用其他解决方案中提到的覆盖函数，但它没有调用

   var dataSets : [LineChartDataSet] = [LineChartDataSet]();
    dataSets.append(getLineChartData(xArr, y: p3Arr,name:"p3",color: UIColor.blueColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p5Arr,name:"p5",color: UIColor.redColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p10Arr,name:"p10",color: UIColor.greenColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p25Arr,name:"p25",color: UIColor.grayColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p50Arr,name:"p50",color: UIColor.purpleColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p75Arr,name:"p75",color: UIColor.yellowColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p90Arr,name:"p90",color: UIColor.orangeColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p95Arr,name:"p95",color: UIColor.brownColor().colorWithAlphaComponent(0.5)))
    dataSets.append(getLineChartData(xArr, y: p97Arr,name:"p97",color: UIColor.cyanColor().colorWithAlphaComponent(0.5)))
    //4 - pass our months in for our x-axis label value along with our dataSets
    let data: LineChartData = LineChartData(xVals: xArr, dataSets: dataSets)
    data.setValueTextColor(UIColor.redColor());

    lineChartView.xAxis.setLabelsToSkip(23);

    lineChartView.pinchZoomEnabled = false;
    lineChartView.doubleTapToZoomEnabled = false;

     //lineChartView.xAxis.valueFormatter?.stringForXValue(12, original: "", viewPortHandler: lineChartView.viewPortHandler)
    lineChartView.data = data

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请出示你用来绘制图表的代码。