How to draw gridBackground by Dashed Line

[anhltse03448]

I want to draw grid background by Dashed Line instead default line. Please help me to solve this issue

[aastein]

chartView.(rightAxis/leftAxis/xAxis).grid*

[liuxuan30]

defined as below:

    public var axisLineColor = NSUIColor.grayColor()
    public var axisLineWidth = CGFloat(0.5)
    public var axisLineDashPhase = CGFloat(0.0)
    public var axisLineDashLengths: [CGFloat]!

    public var gridColor = NSUIColor.grayColor().colorWithAlphaComponent(0.9)
    public var gridLineWidth = CGFloat(0.5)
    public var gridLineDashPhase = CGFloat(0.0)
    public var gridLineDashLengths: [CGFloat]!
    public var gridLineCap = CGLineCap.Butt

    public var drawGridLinesEnabled = true
    public var drawAxisLineEnabled = true

[wmfgithub]

leftAxis.gridLineDashLengths = @[@2];

i forgot to set this property.