Axis ticks support

Source/Charts/Charts/BarLineChartViewBase.swift

@@ -252,6 +252,8 @@ open class BarLineChartViewBase: ChartViewBase, BarLineScatterCandleBubbleChartD
         _xAxisRenderer.renderAxisLabels(context: context)
         _leftYAxisRenderer.renderAxisLabels(context: context)
         _rightYAxisRenderer.renderAxisLabels(context: context)
+        _xAxisRenderer.renderTickLines(context: context)
+        _rightYAxisRenderer.renderTickLines(context: context)
 
         if clipValuesToContentEnabled
         {

Source/Charts/Components/AxisBase.swift

@@ -31,15 +31,20 @@ open class AxisBase: ComponentBase
     open var axisLineWidth = CGFloat(0.5)
     open var axisLineDashPhase = CGFloat(0.0)
     open var axisLineDashLengths: [CGFloat]!
+    open var tickLineColor = NSUIColor.white
 
     open var gridColor = NSUIColor.gray.withAlphaComponent(0.9)
     open var gridLineWidth = CGFloat(0.5)
     open var gridLineDashPhase = CGFloat(0.0)
     open var gridLineDashLengths: [CGFloat]!
     open var gridLineCap = CGLineCap.butt
+    open var tickLineLength = CGFloat(10)
+    open var tickLineWidth = CGFloat(1)
+    open var tickLineOffset = CGFloat(-5)
 
     open var drawGridLinesEnabled = true
     open var drawAxisLineEnabled = true
+    open var drawTickLinesEnabled = true
 
     /// flag that indicates of the labels of this axis should be drawn or not
     open var drawLabelsEnabled = true
@@ -183,6 +188,8 @@ open class AxisBase: ComponentBase
 
     open var isDrawLabelsEnabled: Bool { return drawLabelsEnabled }
 
+    open var isDrawTickLinesEnabled: Bool { return drawTickLinesEnabled }
+
     /// Are the LimitLines drawn behind the data or in front of the data?
     /// 
     /// **default**: false

Source/Charts/Renderers/AxisRendererBase.swift

@@ -58,6 +58,12 @@ open class AxisRendererBase: Renderer
         fatalError("renderLimitLines() cannot be called on AxisRendererBase")
     }
 
+    /// Draws the TickLines associated with this axis to the screen.
+    open func renderTickLines(context: CGContext)
+    {
+        fatalError("renderTickLines() cannot be called on AxisRendererBase")
+    }
+
     /// Computes the axis values.
     /// - parameter min: the minimum value in the data object for this axis
     /// - parameter max: the maximum value in the data object for this axis

Source/Charts/Renderers/XAxisRenderer.swift

@@ -353,6 +353,60 @@ open class XAxisRenderer: AxisRendererBase
         }
     }
 
+    // MARK: - Ticks
+    open override func renderTickLines(context: CGContext)
+    {
+        guard
+            let xAxis = self.axis as? XAxis,
+            let transformer = self.transformer
+            else { return }
+
+        if !xAxis.isDrawTickLinesEnabled
+        {
+            return
+        }
+
+        context.saveGState()
+        defer { context.restoreGState() }
+
+        context.setShouldAntialias(xAxis.gridAntialiasEnabled)
+        context.setStrokeColor(xAxis.tickLineColor.cgColor)
+        context.setLineWidth(xAxis.tickLineWidth)
+        context.setLineCap(xAxis.gridLineCap)
+        context.setLineDash(phase: 0.0, lengths: [])
+
+        let valueToPixelMatrix = transformer.valueToPixelMatrix
+
+        var position = CGPoint(x: 0.0, y: 0.0)
+
+        let entries = xAxis.entries
+
+        for i in stride(from: 0, to: entries.count, by: 1)
+        {
+            position.x = CGFloat(entries[i])
+            position.y = position.x
+            position = position.applying(valueToPixelMatrix)
+
+            drawTickLine(context: context, x: position.x, y: position.y, height: xAxis.tickLineLength)
+        }
+    }
+
+    open func drawTickLine(context: CGContext, x: CGFloat, y: CGFloat, height: CGFloat)
+    {
+        guard
+            let viewPortHandler = self.viewPortHandler
+            else { return }
+
+        if x >= viewPortHandler.offsetLeft
+            && x <= viewPortHandler.chartWidth
+        {
+            context.beginPath()
+            context.move(to: CGPoint(x: x, y: viewPortHandler.contentBottom-height/2))
+            context.addLine(to: CGPoint(x: x, y: viewPortHandler.contentBottom+height/2))
+            context.strokePath()
+        }
+    }
+
     open override func renderLimitLines(context: CGContext)
     {
         guard

Source/Charts/Renderers/YAxisRenderer.swift

@@ -287,6 +287,47 @@ open class YAxisRenderer: AxisRendererBase
         context.drawPath(using: CGPathDrawingMode.stroke)
     }
 
+    // MARK: - Ticks
+    open override func renderTickLines(context: CGContext)
+    {
+        guard let
+            yAxis = self.axis as? YAxis
+            else { return }
+
+        if !yAxis.isDrawTickLinesEnabled
+        {
+            return
+        }
+
+        let positions = transformedPositions()
+
+        context.saveGState()
+        defer { context.restoreGState() }
+
+        context.setShouldAntialias(yAxis.gridAntialiasEnabled)
+        context.setStrokeColor(yAxis.tickLineColor.cgColor)
+        context.setLineWidth(yAxis.tickLineWidth)
+        context.setLineCap(yAxis.gridLineCap)
+
+        // draw the grid
+        for i in 0 ..< positions.count
+        {
+            drawTickLine(context: context, position: positions[i], length: yAxis.tickLineLength, offset: yAxis.tickLineOffset)
+        }
+    }
+
+    open func drawTickLine(context: CGContext, position: CGPoint, length: CGFloat, offset: CGFloat)
+    {
+        guard
+            let viewPortHandler = self.viewPortHandler
+            else { return }
+
+        context.beginPath()
+        context.move(to: CGPoint(x: viewPortHandler.contentRight + offset , y: position.y))
+        context.addLine(to: CGPoint(x: viewPortHandler.contentRight + length + offset, y: position.y))
+        context.strokePath()
+    }
+
     open override func renderLimitLines(context: CGContext)
     {
         guard