Add support for a legend above the chart

Charts/Classes/Charts/BarLineChartViewBase.swift

@@ -409,6 +409,13 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
                     let yOffset = _legend.textHeightMax; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
                     offsetBottom += min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
                 }
+                else if (_legend.position == .AboveChartLeft
+                    || _legend.position == .AboveChartRight
+                    || _legend.position == .AboveChartCenter)
+                {
+                    let yOffset = _legend.textHeightMax; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
+                    offsetTop += min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
+                }
             }
 
             // offsets for y-labels

Charts/Classes/Charts/HorizontalBarChartView.swift

@@ -59,6 +59,13 @@ public class HorizontalBarChartView: BarChartView
                 let yOffset = _legend.textHeightMax * 2.0; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
                 offsetBottom += min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
             }
+            else if (_legend.position == .AboveChartLeft
+                || _legend.position == .AboveChartRight
+                || _legend.position == .AboveChartCenter)
+            {
+                let yOffset = _legend.textHeightMax * 2.0; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
+                offsetTop += min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
+            }
         }
 
         // offsets for y-labels

Charts/Classes/Charts/PieChartView.swift

@@ -340,7 +340,7 @@ public class PieChartView: PieRadarChartViewBase
         }
     }
 
-    internal override var requiredBottomOffset: CGFloat
+    internal override var requiredLegendOffset: CGFloat
     {
         return _legend.font.pointSize * 2.0
     }

Charts/Classes/Charts/PieRadarChartViewBase.swift

@@ -175,10 +175,17 @@ public class PieRadarChartViewBase: ChartViewBase
                     || _legend.position == .BelowChartRight
                     || _legend.position == .BelowChartCenter)
             {
-                let yOffset = self.requiredBottomOffset; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
+                let yOffset = self.requiredLegendOffset; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
                 legendBottom = min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
             }
-
+            else if (_legend.position == .AboveChartLeft
+                || _legend.position == .AboveChartRight
+                || _legend.position == .AboveChartCenter)
+            {
+                let yOffset = self.requiredLegendOffset; // It's possible that we do not need this offset anymore as it is available through the extraOffsets
+                legendTop = min(_legend.neededHeight + yOffset, _viewPortHandler.chartHeight * _legend.maxSizePercent)
+            }
+
             legendLeft += self.requiredBaseOffset
             legendRight += self.requiredBaseOffset
             legendTop += self.requiredBaseOffset
@@ -326,10 +333,10 @@ public class PieRadarChartViewBase: ChartViewBase
         fatalError("radius cannot be called on PieRadarChartViewBase")
     }
 
-    /// - returns: the required bottom offset for the chart.
-    internal var requiredBottomOffset: CGFloat
+    /// - returns: the required offset for the chart legend.
+    internal var requiredLegendOffset: CGFloat
     {
-        fatalError("requiredBottomOffset cannot be called on PieRadarChartViewBase")
+        fatalError("requiredLegendOffset cannot be called on PieRadarChartViewBase")
     }
 
     /// - returns: the base offset needed for the chart without calculating the

Charts/Classes/Charts/RadarChartView.swift

@@ -256,7 +256,7 @@ public class RadarChartView: PieRadarChartViewBase
         }
     }
 
-    internal override var requiredBottomOffset: CGFloat
+    internal override var requiredLegendOffset: CGFloat
     {
         return _legend.font.pointSize * 4.0
     }

Charts/Classes/Components/ChartLegend.swift

@@ -30,6 +30,9 @@ public class ChartLegend: ChartComponentBase
         case BelowChartRight
         case BelowChartCenter
         case PiechartCenter
+        case AboveChartLeft
+        case AboveChartRight
+        case AboveChartCenter
     }
 
     @objc
@@ -235,7 +238,10 @@ public class ChartLegend: ChartComponentBase
         }
         else if (position == .BelowChartLeft
             || position == .BelowChartRight
-            || position == .BelowChartCenter)
+            || position == .BelowChartCenter
+            || position == .AboveChartLeft
+            || position == .AboveChartRight
+            || position == .AboveChartCenter)
         {
             var labels = self.labels
             var colors = self.colors

Charts/Classes/Renderers/ChartLegendRenderer.swift

@@ -139,13 +139,16 @@ public class ChartLegendRenderer: ChartRendererBase
         {
         case .BelowChartLeft: fallthrough
         case .BelowChartRight: fallthrough
-        case .BelowChartCenter:
+        case .BelowChartCenter: fallthrough
+        case .AboveChartLeft: fallthrough
+        case .AboveChartRight: fallthrough
+        case .AboveChartCenter:
 
             let contentWidth: CGFloat = viewPortHandler.contentWidth
 
             var originPosX: CGFloat
 
-            if (legendPosition == .BelowChartLeft)
+            if (legendPosition == .BelowChartLeft || legendPosition == .AboveChartLeft)
             {
                 originPosX = viewPortHandler.contentLeft + xoffset
 
@@ -154,7 +157,7 @@ public class ChartLegendRenderer: ChartRendererBase
                     originPosX += _legend.neededWidth
                 }
             }
-            else if (legendPosition == .BelowChartRight)
+            else if (legendPosition == .BelowChartRight || legendPosition == .AboveChartRight)
             {
                 originPosX = viewPortHandler.contentRight - xoffset
 
@@ -174,6 +177,12 @@ public class ChartLegendRenderer: ChartRendererBase
 
             var posX: CGFloat = originPosX
             var posY: CGFloat = viewPortHandler.chartHeight - yoffset - _legend.neededHeight
+            if (legendPosition == .AboveChartLeft
+                || legendPosition == .AboveChartRight
+                || legendPosition == .AboveChartCenter)
+            {
+                posY = 0;
+            }
 
             var lineIndex: Int = 0