How can I show first value and last value in line Chart - ios

Question

I'm using charts library and i'm trying to add first value and last value on line chart graph.Please let me know how can I achieve it. I have tried customising drawValue method in linechartrenderer but didn't worked.
Here is my code
var months = ["Dec 15", "Jun 16", "Dec 16", "Jun 17", "Dec 17", "Jun 18"]
var unitsSold = [50.0, 25.0, 50.0, 75.0, 100.0, 75.0]
Viewdidload:
setChart(dataPoints: months, values: unitsSold)
Method:
func setChart(dataPoints: [String], values: [Double]) {
var dataEntries: [ChartDataEntry] = []
for i in 0..<dataPoints.count {
let dataEntry = ChartDataEntry(x: Double(i), y: values[i], data: dataPoints[i] as AnyObject)
dataEntries.append(dataEntry)
}
let chartDataSet = LineChartDataSet(values: dataEntries, label: nil)
chartDataSet.setColor(UIColor(red: 53/255, green: 85/255, blue: 123/255, alpha: 1))
chartDataSet.circleRadius = 5
chartDataSet.circleHoleRadius = 2
chartDataSet.drawValuesEnabled = false
chartDataSet.drawCirclesEnabled = false
let chartData = LineChartData(dataSets: [chartDataSet])
defaultChartView.data = chartData
defaultChartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: months)
defaultChartView.xAxis.labelPosition = .bottom
defaultChartView.xAxis.drawGridLinesEnabled = false
//lineChartView.xAxis.avoidFirstLastClippingEnabled = true
defaultChartView.xAxis.axisMinimum = 0
defaultChartView.xAxis.granularity = 1
defaultChartView.rightAxis.drawAxisLineEnabled = false
defaultChartView.rightAxis.drawLabelsEnabled = false
defaultChartView.rightAxis.enabled = false
defaultChartView.leftAxis.drawAxisLineEnabled = false
defaultChartView.leftAxis.axisMinimum = 0.0
defaultChartView.leftAxis.drawLabelsEnabled = false
//lineChartView.leftAxis.drawGridLinesEnabled = false
//lineChartView.leftAxis.granularityEnabled = false
defaultChartView.pinchZoomEnabled = true
defaultChartView.doubleTapToZoomEnabled = true
defaultChartView.legend.enabled = false
defaultChartView.chartDescription?.text = " "
}

Answer 1

viewDidLoad:
guard let firstMonth = months.first, let lastMonth = months.last else {
return
}
let myMonths = [firstMonth, lastMonth]
guard let firstValue = unitsSold.first, let lastValue = unitsSold.last else {
return
}
let myValues = [firstValue, lastValue]
setChart(dataPoints: myMonths, values: myValues)

Answer 2

Solution is go to linechartrenderer file and replace drawValues method
open override func drawValues(context: CGContext)
{
guard
let dataProvider = dataProvider,
let lineData = dataProvider.lineData
else { return }
if isDrawingValuesAllowed(dataProvider: dataProvider)
{
var dataSets = lineData.dataSets
let phaseY = animator.phaseY
var pt = CGPoint()
for i in 0 ..< dataSets.count
{
guard let dataSet = dataSets[i] as? ILineChartDataSet else { continue }
if !shouldDrawValues(forDataSet: dataSet)
{
continue
}
let valueFont = dataSet.valueFont
guard let formatter = dataSet.valueFormatter else { continue }
let trans = dataProvider.getTransformer(forAxis: dataSet.axisDependency)
let valueToPixelMatrix = trans.valueToPixelMatrix
let iconsOffset = dataSet.iconsOffset
// make sure the values do not interfear with the circles
var valOffset = Int(dataSet.circleRadius * 1.75)
if !dataSet.isDrawCirclesEnabled
{
valOffset = valOffset / 2
}
_xBounds.set(chart: dataProvider, dataSet: dataSet, animator: animator)
for j in stride(from: _xBounds.min, through: min(_xBounds.min + _xBounds.range, _xBounds.max), by: 1)
{
guard let e = dataSet.entryForIndex(j) else { break }
if(j == 0 || j == dataSet.entryCount - 1)
{
pt.x = CGFloat(e.x)
pt.y = CGFloat(e.y * phaseY)
pt = pt.applying(valueToPixelMatrix)
if (!viewPortHandler.isInBoundsRight(pt.x))
{
break
}
if (!viewPortHandler.isInBoundsLeft(pt.x) || !viewPortHandler.isInBoundsY(pt.y))
{
continue
}
if dataSet.isDrawValuesEnabled {
ChartUtils.drawText(
context: context,
text: formatter.stringForValue(
e.y,
entry: e,
dataSetIndex: i,
viewPortHandler: viewPortHandler),
point: CGPoint(
x: pt.x,
y: pt.y - CGFloat(valOffset) - valueFont.lineHeight),
align: .center,
attributes: [NSAttributedStringKey.font: valueFont, NSAttributedStringKey.foregroundColor: dataSet.valueTextColorAt(j)])
}
if let icon = e.icon, dataSet.isDrawIconsEnabled
{
ChartUtils.drawImage(context: context,
image: icon,
x: pt.x + iconsOffset.x,
y: pt.y + iconsOffset.y,
size: icon.size)
}
}
else{
}
}
}
}
}

Answer 3

Set below property of X axis
barChartView.xAxis.setLabelCount(2, force: true)