Multiple colors for valueline (Fixes #3480)

Source/Charts/Data/Implementations/Standard/PieChartDataSet.swift

@@ -84,6 +84,9 @@ open class PieChartDataSet: ChartDataSet, IPieChartDataSet
     /// When valuePosition is OutsideSlice, indicates line color
     open var valueLineColor: NSUIColor? = NSUIColor.black
 
+    /// When valuePosition is OutsideSlice and enabled, line will have the same color as the slice
+    open var valueLineAutoColor: Bool = false
+
     /// When valuePosition is OutsideSlice, indicates line width
     open var valueLineWidth: CGFloat = 1.0
 

Source/Charts/Data/Interfaces/IPieChartDataSet.swift

@@ -38,6 +38,9 @@ public protocol IPieChartDataSet: IChartDataSet
     /// When valuePosition is OutsideSlice, indicates line color
     var valueLineColor: NSUIColor? { get set }
 
+    /// When valuePosition is OutsideSlice and enabled, line will have the same color as the slice
+    var valueLineAutoColor: Bool { get set }
+
     /// When valuePosition is OutsideSlice, indicates line width
     var valueLineWidth: CGFloat { get set }
 

Source/Charts/Renderers/PieChartRenderer.swift

@@ -440,7 +440,11 @@ open class PieChartRenderer: DataRenderer
 
                     if dataSet.valueLineColor != nil
                     {
-                        context.setStrokeColor(dataSet.valueLineColor!.cgColor)
+                        if dataSet.valueLineAutoColor {
+                            context.setStrokeColor(dataSet.color(atIndex: j).cgColor)
+                        } else {
+                            context.setStrokeColor(dataSet.valueLineColor!.cgColor)
+                        }
                         context.setLineWidth(dataSet.valueLineWidth)
 
                         context.move(to: CGPoint(x: pt0.x, y: pt0.y))