图表：如何在LineChartView中设置左右轴标签的颜色？

Question

我的图形使用自定义IAxisValueFormatters来设置左右轴标签（如下）。我尝试过使用左右两边的labelTextColor属性（如下），但是它们没有改变标签的字体颜色。

class myViewController {

    func initalizeGraph() {

        //omitted for brevity

        let leftYAxisValueFormatter = SpeedAndHRLeftYAxisValueFormatter(measurementSystem: measurementSystem)
        lineChartView.leftAxis.labelTextColor = iPhoneThemeColor1
        lineChartView.leftAxis.valueFormatter = leftYAxisValueFormatter

        let rightYAxisValueFormatter = SpeedAndHRRightYAxisValueFormatter()
        lineChartView.rightAxis.labelTextColor = iPhoneThemeColor2
        lineChartView.rightAxis.valueFormatter = rightYAxisValueFormatter
    }
}

class SpeedAndHRLeftYAxisValueFormatter: IAxisValueFormatter {
    //left side is speed

    //multiplu value x 40 (.5 * x = 20?)
    var measurementSystem: MeasurementSystem

    init(measurementSystem: MeasurementSystem) {
        self.measurementSystem = measurementSystem
    }

    func stringForValue(_ value: Double, axis: AxisBase?) -> String {

        let intValue = Int(value * 40)
        var suffixString = ""

        switch measurementSystem {
        case .US:
            suffixString =  "mph"
        case .Metric:
            suffixString = "km/h"
        }

        return "\(intValue)" + " " + suffixString
    }
}

class SpeedAndHRRightYAxisValueFormatter: IAxisValueFormatter {
    //right side is HR

    func stringForValue(_ value: Double, axis: AxisBase?) -> String {

        let intValue = Int(value * 210)

        return "\(intValue)" + " " + "bpm"
    }
}

Answer 1

您必须在viewDidLoad()方法中添加以下代码。在我的一个项目中，这对我来说确实很有效。

override func viewDidLoad() {

    let leftYAxisValueFormatter = SpeedAndHRLeftYAxisValueFormatter(measurementSystem: measurementSystem)
    lineChartView.leftAxis.valueFormatter = leftYAxisValueFormatter
    lineChartView.leftAxis.labelTextColor = iPhoneThemeColor1

    let rightYAxisValueFormatter = SpeedAndHRRightYAxisValueFormatter()
    lineChartView.rightAxis.valueFormatter = rightYAxisValueFormatter
    lineChartView.rightAxis.labelTextColor = iPhoneThemeColor2
}

此外，请按照以下步骤更新用于创建类的代码：

@objc(LineChartFormatter)
class SpeedAndHRRightYAxisValueFormatter:NSObject, IAxisValueFormatter {
    ....
    //Your Code
    ....
}

@objc(LineChartFormatter)
class SpeedAndHRLeftYAxisValueFormatter:NSObject, IAxisValueFormatter {
    ....
    //Your Code
    ....
}

我希望这会对您有所帮助。