Change Tick Labels for Coreplot Graph

问题

I am using coreplot for graphs in my mac application & its working fine. I have a requirement to show custom labels along the axis for ticks like :

I have a graph for power values against time : Power values -> Y-Axis & Time -> X-Axis.

I want to draw graph for Time seconds values but show fixed intervals ticks of minutes along x-axis for which i figured that i should use custom labels but its not happening for me.

Code for custom labels is :

  let graph = CPTXYGraph()

  plots[0].identifier = PlotType.target.rawValue
  plots[1].identifier = PlotType.user.rawValue

  for plot in plots {
     plot.dataSource = self
     plot.delegate = self
     graph.addPlot(plot)
  }

  if let plotArea = graph.plotAreaFrame {
     plotArea.borderLineStyle = nil
     plotArea.paddingLeft = 25.0
     plotArea.paddingBottom = 20.0
     plotArea.paddingRight = 10.0
     plotArea.paddingTop = 20.0
  }

  guard let axisSet = graph.axisSet else { return }

  let xAxis = axisSet.axes?[0]
  var xLabels = [CPTAxisLabel]()
  var xLocations = [NSNumber]()

  let doubleSecs = Double(activity.durationSeconds)
  let labels = [0.0, doubleSecs * 0.25, doubleSecs * 0.50, doubleSecs * 0.75, doubleSecs]
  for label in labels {
     let xLabel = CPTAxisLabel(text: "\(label/60)", textStyle: axisTextStyle)
     xLabel.tickLocation = NSNumber(double: label)
     xLocations.append(NSNumber(double: label))
     xLabels.append(xLabel)
  }
  xAxis?.labelingPolicy = CPTAxisLabelingPolicy.LocationsProvided
  xAxis?.labelFormatter = axisFormatter
  xAxis?.axisLabels = Set(xLabels)
  xAxis?.majorTickLocations = Set(xLocations)

  chartView.hostedGraph = graph

With above code it is drawing graph & along x-axis it is dividing time in 4 equal portions & showing labels, everything is good.

I want to show labels along x-axis as minutes and remaining drawing is ok.

I tried with this : let xLabel = CPTAxisLabel(text: "\(label/60)", textStyle: axisTextStyle()) but labels are not changing no effect.

Also tried to change tickLocation like : xLabel.tickLocation = NSNumber(double: label/60) No effect

With changing majorTickLocations like : xLocations.append(NSNumber(double: label/60)) it behaving weird and all x-axis labels are messed.

I tried to follow this example : StackOverFlow Post

Can anyone guide whats going wrong [Remember I am using Swift] ?

回答1:

The .LocationsProvided labeling policy uses the labelFormatter to create labels from the tick locations automatically. If you want to use custom labels, use the .None labeling policy instead.

回答2:

I solved it myself by doing it like :

  let xAxis = axisSet.axes?[0]
  xAxis?.majorIntervalLength = activity.durationSeconds / 60 / 4
  xAxis?.labelingPolicy = CPTAxisLabelingPolicy.FixedInterval

Now labels are coming as required.

来源：https://stackoverflow.com/questions/36614204/change-tick-labels-for-coreplot-graph