IOS 使用 Swift X 轴问题的图表

Question

我最近升级到最新版本的 IOS 图表和 X 代码 (8.3)，但我在使用 IOS 图表和我的 x 轴时遇到问题。我的 x 轴支持显示日期，但自从升级后我无法让它工作，我只能得到 0 到 6。我相信我知道为什么，这是因为我似乎无法设置 X-轴值了。

这里是升级前的原代码：

func setChart(_ dataPoints: [String], values: [Double]) {

    var dataEntries: [ChartDataEntry] = []

    for i in 0..<dataPoints.count {
        let dataEntry = ChartDataEntry(value: values[i], xIndex: i)
        dataEntries.append(dataEntry)
    }

    let lineChartDataSet = LineChartDataSet(yVals: dataEntries, label: "Total Items")
    let lineChartData = LineChartData(xVals: dataPoints, dataSet: lineChartDataSet)

    lineChartDataSet.colors = [UIColor(red: 27.0/255.0, green: 114.0/255.0, blue: 216.0/255.0, alpha: 1.0)]
    lineChartView.xAxis.labelPosition = .bottom
    lineChartView.xAxis.labelFont = UIFont(name: "AvenirNext-Medium", size: 8.0)!
    lineChartView.legend.enabled = false
    lineChartView.animate(xAxisDuration: 2.0, yAxisDuration: 2.0, easingOption: .easeInOutQuad)
    lineChartView.chartDescription?.text = ""
    lineChartView.rightAxis.enabled = false
    lineChartView.leftAxis.labelFont = UIFont(name: "AvenirNext-Medium", size: 8.0)!
    lineChartDataSet.drawValuesEnabled = false
    lineChartDataSet.drawCirclesEnabled = false
    lineChartDataSet.lineWidth = 2.0
    lineChartView.leftAxis.valueFormatter = NumberFormatter()
    lineChartView.leftAxis.valueFormatter.minimumFractionDigits = 0
    lineChartView.isUserInteractionEnabled = false
    lineChartView.data = lineChartData

}

所以这总是工作正常，因为升级的东西已经改变了，所以我的代码现在是：

func setChart(_ dataPoints: [String], values: [Double]) {

    var dataEntries: [ChartDataEntry] = []

    for i in 0..<dataPoints.count {
        let dataEntry = ChartDataEntry(x: Double(i), y: values[i])
        dataEntries.append(dataEntry)
    }

    let lineChartDataSet = LineChartDataSet(values: dataEntries, label: "Total Items")
    let lineChartData = LineChartData(dataSet: lineChartDataSet)

    lineChartDataSet.colors = [UIColor(red: 27.0/255.0, green: 114.0/255.0, blue: 216.0/255.0, alpha: 1.0)]
    lineChartView.xAxis.labelPosition = .bottom
    lineChartView.xAxis.labelFont = UIFont(name: "AvenirNext-Medium", size: 8.0)!
    lineChartView.legend.enabled = false
    lineChartView.animate(xAxisDuration: 2.0, yAxisDuration: 2.0, easingOption: .easeInOutQuad)
    lineChartView.chartDescription?.text = ""
    lineChartView.rightAxis.enabled = false
    lineChartView.leftAxis.labelFont = UIFont(name: "AvenirNext-Medium", size: 8.0)!
    lineChartDataSet.drawValuesEnabled = false
    lineChartDataSet.drawCirclesEnabled = false
    lineChartDataSet.lineWidth = 2.0
    lineChartView.leftAxis.valueFormatter = NumberFormatter() as? IAxisValueFormatter
    //lineChartView.leftAxis.valueFormatter.minimumFractionDigits = 0
    lineChartView.isUserInteractionEnabled = false
    lineChartView.data = lineChartData

}

所以之前我在 lineChartData 中设置 x 轴值，但现在我不能这样做，所以我认为我的 x 轴数据没有被设置。任何人都可以帮助让我的日期再次显示在我的 x 轴上吗？

谢谢

戴夫

Answer 1

您需要使用 stringForValue 方法实现 IAxisValueFormatter 协议并将其设置为 xAxis.valueFormatter

的委托

我看到了两种方式。

您只需将 IAxisValueFormatter 协议添加到 ViewController 并在您的 ViewController.

中实现 stringForValue

class ViewController: UIViewController, IAxisValueFormatter {

    // your code ...

    // implement delegate method
    func stringForValue(_ dataPointIndex: Double, axis: AxisBase?) -> String {

        return someDataPoints[Int(dataPointIndex)]
    }

    func setChart(dataPoints: [String], values: [Double]){
        // your code ...

        // Set delegate 
        lineChartView.xAxis.valueFormatter = self
    }

    // your code ...
}

或者您可以为 IAxisValueFormatter 协议创建特定委托 class。

private class DataPointFormatter: NSObject, IAxisValueFormatter {

    var dataPoints: [String] = []

    func stringForValue(_ value: Double, axis: AxisBase?) -> String {
        return dataPoints[Int(value)]
    }

    init(dataPoints: [String]) {
        super.init()
        self.dataPoints = dataPoints
    }
}

然后在您的 setChart 函数中设置委托

func setChart(dataPoints: [String], values: [Double]){
    // your code ...

    lineChartView.xAxis.valueFormatter = DataPointFormatter(dataPoints: dataPoints)
}

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