如何在 iOS 图表的 X 轴上添加字符串？

Question

对于新版本，我在创建一些图表时遇到了一些麻烦，之前的代码是：

func setChart(dataPoints: [String], values: [Double]) {
    var dataEntries: [BarChartDataEntry] = []

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

    let chartDataSet = BarChartDataSet(yVals: dataEntries, label: "Units Sold")
    let chartData = BarChartData(xVals: months, dataSet: chartDataSet)
    barChartView.data = chartData
}

您可以使用以下行传递值，例如月份数组：

let chartData = BarChartData(xVals: months, dataSet: chartDataSet)

新版本发布后实现相同图表的代码为：

func setChart(dataPoints: [String], values: [Double]) {          
    var dataEntries: [BarChartDataEntry] = []

    for i in 0..<dataPoints.count {
        let dataEntry = BarChartDataEntry(x: Double(i+2), y:values[i], data: months )
        dataEntries.append(dataEntry)
    }

    let chartDataSet = BarChartDataSet(values: dataEntries, label: "Units Sold")

    let chartData = BarChartData()
    chartData.addDataSet(chartDataSet)
    barChartView.data = chartData
}

我尝试了几个小时，但找不到修改 X 轴值的方法，希望有人能帮助我，谢谢！！

Answer 1

我找到了解决方案，也许另一个可以更好地解决这个问题，而无需创建新的 class，这就是我找到的：

首先你需要创建一个新的class，这将是你的格式化程序class并添加 IAxisValueFormater 接口，然后你使用方法 stringForValue 来自定义新值，它需要两个参数，第一个是实际值（你可以像索引一样看到它）第二个是值所在的轴。

import UIKit
import Foundation
import Charts

@objc(BarChartFormatter)
public class BarChartFormatter: NSObject, IAxisValueFormatter
{
  var months: [String]! = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]

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

现在，在您的文件中，在 setChart() 函数的开头，您必须创建两个变量，一个用于格式化程序 class，一个用于轴 class:

let formato:BarChartFormatter = BarChartFormatter()
let xaxis:XAxis = XAxis()

接下来，在 for in 循环的末尾继续并将索引和轴传递给格式化程序变量：

formato.stringForValue(Double(i), axis: xaxis)

循环后将格式添加到轴变量：

xaxis.valueFormatter = formato

最后一步是将新的 xaxisformatted 添加到 barChartView：

barChartView.xAxis.valueFormatter = xaxis.valueFormatter

这就是 setChart() 函数中的所有其他行，请将其保留在原处，希望对您有所帮助。

Answer 2

如果您对图进行子类化，则实施上述建议的一种更简洁的方法是在您的子类本身中实施 IAxisValueFormatter 协议

class CustomGraphView : LineChartView, ChartViewDelegate, IAxisValueFormatter {}

像这样...

public func stringForValue(_ value: Double, axis: Charts.AxisBase?) -> String
{
    return "My X Axis Label Str";  // Return you label string, from an array perhaps.
}

然后在你的 init()

self.xAxis.valueFormatter = self;

Answer 3

你好，最近遇到了同样的问题，是这样解决的-

class ViewController: UIViewController {

    var months: [String]!
    var unitsSold = [Double]()
    weak var axisFormatDelegate: IAxisValueFormatter?

    @IBOutlet var viewForChart: BarChartView!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        axisFormatDelegate = 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(_ dataPoints:months,_ forY: unitsSold)
        setChart(dataEntryX: months, dataEntryY: unitsSold)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    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{
           // print(forX[i])
           // let dataEntry = BarChartDataEntry(x: (forX[i] as NSString).doubleValue, y: Double(unitsSold[i]))
            let dataEntry = BarChartDataEntry(x: Double(i), y: Double(forY[i]) , data: months as AnyObject?)
            print(dataEntry)
            dataEntries.append(dataEntry)
        }
        let chartDataSet = BarChartDataSet(values: dataEntries, label: "Units Sold")
        let chartData = BarChartData(dataSet: chartDataSet)
        viewForChart.data = chartData
        let xAxisValue = viewForChart.xAxis
        xAxisValue.valueFormatter = axisFormatDelegate

    }
}

最后简单地添加委托的扩展

extension ViewController: IAxisValueFormatter {

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

通过这个 link 想出了这个解决方案 https://medium.com/@skoli/using-realm-and-charts-with-swift-3-in-ios-10-40c42e3838c0#.minfe6kuk

Answer 4

正如许多人所说，您可以创建一个 class 或使用 IAxisValueFormatter 类型进行扩展，但您可以轻松地使用以下仅需要 3 行的方法：

self.chartView.xAxis.valueFormatter = DefaultAxisValueFormatter(block: {(index, _) in
    return xStrings[Int(index)]
})

这是我的 setChart() 函数，以防你们中的一些人觉得我的一些定制很有趣：

func setChartView(entriesData: [entry]) {
    var chartEntries: [ChartDataEntry] = []
    var xStrings: [String] = []
    let sortedentriesData = entriesData.sorted { (s1: entry, s2: entry) -> Bool in
        return s1.timestamp < s2.timestamp
    }
    for (i, entry) in sortedentriesData.enumerated() {
        let newEntry = ChartDataEntry(x: Double(i), y: entry.temperature)
        chartEntries.append(newEntry)
        let dateFormatter = DateFormatter()
        dateFormatter.timeStyle = .medium
        dateFormatter.dateStyle = .none
        xStrings.append("\(dateFormatter.string(from: Date.init(timeIntervalSince1970: TimeInterval(entry.timestamp))))")
    }
    let set: LineChartDataSet = LineChartDataSet(values: chartEntries, label: "°C")
    set.setColor(NSUIColor.blue, alpha: CGFloat(1))
    set.circleColors = [NSUIColor.blue]
    set.circleRadius = 3
    set.mode = LineChartDataSet.Mode.cubicBezier

    let data: LineChartData = LineChartData(dataSet: set)
    self.chartView.xAxis.labelRotationAngle = -90
    self.chartView.xAxis.valueFormatter = DefaultAxisValueFormatter(block: {(index, _) in
        return xStrings[Int(index)]
    })
    self.chartView.xAxis.setLabelCount(xStrings.count, force: true)
    self.chartView.data = data
}

条目是我创建的结构：

struct entry {
    var timestamp: Int
    var temperature: Double
}

Answer 5

最简单的解决方案：

barChartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: months)
barChartView.xAxis.granularity = 1

Answer 6

我是这样实现的，我有 "yyyy-MM-dd HH:mm" 格式的日期，我想在 x 轴的字符串中显示 "HH:mm"。这是代码，

我使用立方线图表，首先我在图表上设置数据

func setDataCount() {

    var dataEntries: [ChartDataEntry] = []
    let formatter = CubicChartFormatter()
    let xaxis:XAxis = XAxis()
    if graphArray?.count ?? 0>0 {
        for i in 0..<graphArray!.count {
            let dateFormatter = DateFormatter()
            dateFormatter.dateFormat = "yyyy-MM-dd HH:mm"
            let date = dateFormatter.date(from:graphArray![i].writetime)
            let formatingDate = getFormattedDate(date: date!, format: "HH:mm")
            xDataPoints.append(formatingDate)
            formatter.setValues(values: xDataPoints)
            let dataEntry = ChartDataEntry(x: Double(i), y: Double(yVal)!, data: formatingDate)
            dataEntries.append(dataEntry)
            let set1 = LineChartDataSet(entries: dataEntries, label: "DataSet")
            let data = LineChartData(dataSet: set1)
            chartView.xAxis.valueFormatter = formatter
            chartView.data = data
        }
    }
}

并制作格式Class

@objc(CubicChartFormatter)
public class CubicChartFormatter: NSObject, IAxisValueFormatter
{
   var names = [String]()

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

   public func setValues(values: [String])
   {
      self.names = values
   } 
}

如何在 iOS 图表的 X 轴上添加字符串？

How to add Strings on X Axis in iOS-charts?

ios

swift

ios-charts