如何在SWIFT 3x中实现跟踪球和访问条形图上的标签

问题描述

开发人员您好，我正在做的项目中我使用了Danielgindi/Charts第三方库现在这里的挑战是我需要在图表的最高点展示一个如图所示的跟踪球。我如何实现这一点有什么建议吗？ 或者如何访问条形图上方的值，我想在最高峰(20.0)上打印其他内容，如"E"？？

推荐答案

不幸的是，无法设置图像，而不是在条形图上方的值处设置字符串或双精度。 但是，是的，我们可以访问上面的值栏，请访问提到的链接。 https://github.com/danielgindi/Charts/issues/2126

class ViewController: UIViewController {
    var chartData = BarChartData()
    var months: [String]!
    var unitsSold = [Double]()
 weak var valueFormatter: IValueFormatter?
   @IBOutlet var viewForChart: BarChartView!
override func viewDidLoad() {
        super.viewDidLoad()
valueFormatter = self

        months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
        unitsSold = [20.0, 4.0, 6.0, 3.0, 12.0, 16.0, 4.0, 18.0, 2.0, 4.0, 5.0, 4.0]

 setChart(dataEntryX: months, dataEntryY: unitsSold)
}

    func setChart(dataEntryX forX:[String],dataEntryY forY: [Double]) {
        viewForChart.noDataText = "You need to provide data for the chart."
        var dataEntries:[BarChartDataEntry] = []
        for i in 0..<forX.count{

            let dataEntry = BarChartDataEntry(x: Double(i), y:  Double(forY[i]) , data: months as AnyObject?)
     dataEntries.append(dataEntry)
        }

        let chartDataSet = BarChartDataSet(values: dataEntries, label: "Units Sold")
       chartDataSet.setColor(UIColor.brown, alpha: 0.30)
        chartData = BarChartData(dataSet: chartDataSet)
chartData.barWidth = 0.75
        chartData.setDrawValues(true)
        viewForChart.data = chartData
viewForChart.xAxis.valueFormatter = IndexAxisValueFormatter(values: months)

        viewForChart.drawBordersEnabled = false

  viewForChart.data?.setValueFormatter(valueFormatter)
 }
}

在类的上方或之外添加扩展

extension ViewController: IValueFormatter {
    func stringForValue(_ value: Double, entry: ChartDataEntry, dataSetIndex: Int, viewPortHandler: ViewPortHandler?) -> String {
        print(value)
        //logic to print string at required point or value
        switch value {

        case 20.0: return ""
        default: return ""
        }
    }
}