iOS Charts ValueFormatter

Question

I am using iOS charts plugin (line chart) and wish to style the chart values (the number above each point) to a decimal number.

The value is a double, but charts by default is rounding it and displaying it as an integer.

I have tried the following but not working:

    let valueformatter = NumberFormatter()
    valueformatter.numberStyle = .decimal
    valueformatter.locale = Locale.current
    lineChartDataSet.valueFormatter = valueformatter as? IValueFormatter

I have tried various other properties but non of them change the format of the number in the dataset.

How can I change the format of the displayed number?

score 16 · Accepted Answer · edited Jan 16 '23 at 06:04

16

Almost there, just need to add the following class:

//For old Charts version
//class ChartValueFormatter: NSObject, IValueFormatter {

//For Charts version 4.0.1
class ChartValueFormatter: NSObject, ValueFormatter {
    fileprivate var numberFormatter: NumberFormatter?

    convenience init(numberFormatter: NumberFormatter) {
        self.init()
        self.numberFormatter = numberFormatter
    }

    func stringForValue(_ value: Double, entry: ChartDataEntry, dataSetIndex: Int, viewPortHandler: ViewPortHandler?) -> String {
        guard let numberFormatter = numberFormatter
            else {
                return ""
        }
        return numberFormatter.string(for: value)!
    }
}

Now use this as the number formatter:

let numberFormatter = NumberFormatter()
numberFormatter.numberStyle = .decimal
numberFormatter.locale = Locale.current
let valuesNumberFormatter = ChartValueFormatter(numberFormatter: numberFormatter)
lineChartDataSet.valueFormatter = valuesNumberFormatter
lineChartDataSet.valueFont = lineChartDataSet.valueFont.withSize(chartFontPointSize)

edited Jan 16 '23 at 06:04

Bhadresh Kathiriya

3,147
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answered Jun 28 '17 at 23:28

George Filippakos

16,359
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Thanks so much. This code changes numbers in chart. Is there any way to format xAxis.valueFormatter ? – Milad Faridnia Oct 31 '17 at 10:27
can u tell me what should i do this type 10.000% of data set with using your number formatter method . – ronak patel Jan 23 '18 at 12:24
@ronak-patel not sure what you mean - maybe try using .percentstyle for the numberStyle – George Filippakos Jan 23 '18 at 19:46
George Filippakos any way I could pick your brain a bit on using Dates on an X axis for iOS charts? – BostonMacOSX May 21 '18 at 13:49

score 7 · Answer 2 · answered Oct 29 '18 at 17:34

7

   lineChartDataSet.valueFormatter = DefaultValueFormatter(decimals: 2)

answered Oct 29 '18 at 17:34

Jiebe

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It was helpful. With a slight correction: chartView.data?.setValueFormatter(DefaultValueFormatter(decimals: 2)) – Grzegorz R. Kulesza Dec 20 '18 at 10:16

score 6 · Answer 3 · answered Jul 20 '19 at 23:56

This worked for me:

Swift 5

let valFormatter = NumberFormatter()
valFormatter.numberStyle = .currency
valFormatter.maximumFractionDigits = 2
valFormatter.currencySymbol = "$"

lineChartPrice.leftAxis.valueFormatter = DefaultAxisValueFormatter(formatter: valFormatter)

score 3 · Answer 4 · answered Feb 15 '19 at 17:43

 let data = PieChartData(dataSet: set) 

 let formatter = NumberFormatter() 
 formatter.numberStyle = .percent 
 formatter.maximumFractionDigits = 2 
 formatter.multiplier = 1.0 
 formatter.percentSymbol = "%" 
 formatter.zeroSymbol = "" 
 data.setValueFormatter(DefaultValueFormatter(formatter: formatter))

iOS Charts ValueFormatter

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