fix #1830. credit from https://github.com/danielgindi/Charts/pull/2049

Charts.xcodeproj/project.pbxproj

@@ -107,6 +107,7 @@
 		B0D28C68BB9A958DC56EB214 /* DefaultValueFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 107D8F8163EE54D6D9E916B0 /* DefaultValueFormatter.swift */; };
 		B13C74B4FF705D7B595D01EF /* IAxisValueFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0BD9DF16AF59680A3BB49452 /* IAxisValueFormatter.swift */; };
 		B539114951455C35BADAE3F3 /* PieChartDataSet.swift in Sources */ = {isa = PBXBuildFile; fileRef = A4FB5E3761EF8B4D1E1E1014 /* PieChartDataSet.swift */; };
+		B6BF9A561F91993A00E62A5D /* CombinedChartTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B6BF9A551F91993A00E62A5D /* CombinedChartTests.swift */; };
 		B6C9F450D937B87224D29D5C /* IFillFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 818AC6B12505B7C0A53D62F9 /* IFillFormatter.swift */; };
 		B6DCC229615EFE706F64A37D /* LineScatterCandleRadarRenderer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 923206233CA89FD03565FF87 /* LineScatterCandleRadarRenderer.swift */; };
 		B85DEB06B4C1AFFC8A0E3295 /* CircleShapeRenderer.swift in Sources */ = {isa = PBXBuildFile; fileRef = ECE1B1623D3AF69CECAE8562 /* CircleShapeRenderer.swift */; };
@@ -264,6 +265,7 @@
 		B137428B41C143D5115726C4 /* Description.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = Description.swift; path = Source/Charts/Components/Description.swift; sourceTree = "<group>"; };
 		B1BA6B21CBDF77A15848994F /* RadarChartDataSet.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = RadarChartDataSet.swift; path = Source/Charts/Data/Implementations/Standard/RadarChartDataSet.swift; sourceTree = "<group>"; };
 		B44829AF0ADA583F1F0279B7 /* BubbleChartDataSet.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = BubbleChartDataSet.swift; path = Source/Charts/Data/Implementations/Standard/BubbleChartDataSet.swift; sourceTree = "<group>"; };
+		B6BF9A551F91993A00E62A5D /* CombinedChartTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = CombinedChartTests.swift; path = Tests/Charts/CombinedChartTests.swift; sourceTree = "<group>"; };
 		BA157EFF2F952192C11DF937 /* AnimatedMoveViewJob.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = AnimatedMoveViewJob.swift; path = Source/Charts/Jobs/AnimatedMoveViewJob.swift; sourceTree = "<group>"; };
 		BA1A58428DC4780BAB4EAADC /* CandleStickChartView.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = CandleStickChartView.swift; path = Source/Charts/Charts/CandleStickChartView.swift; sourceTree = "<group>"; };
 		BC19DC2434D65FFB446A61B7 /* XAxisRendererRadarChart.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; name = XAxisRendererRadarChart.swift; path = Source/Charts/Renderers/XAxisRendererRadarChart.swift; sourceTree = "<group>"; };
@@ -511,6 +513,7 @@
 			children = (
 				5C3F5E1A69EC06E86505F7B1 /* BarChartTests.swift */,
 				7AB9062A28AAB9469752A954 /* ChartUtilsTests.swift */,
+				B6BF9A551F91993A00E62A5D /* CombinedChartTests.swift */,
 				D2E1819D72CD7B6C4A4E8048 /* LineChartTests.swift */,
 				064989451F5C99C7006E8BB3 /* Snapshot.swift */,
 			);
@@ -943,6 +946,7 @@
 			files = (
 				3B11556EB7DC034E2FC958E4 /* BarChartTests.swift in Sources */,
 				8E1192F7A7152E9DA92C56A9 /* ChartUtilsTests.swift in Sources */,
+				B6BF9A561F91993A00E62A5D /* CombinedChartTests.swift in Sources */,
 				2BF85BEA981B359A65E9BF67 /* LineChartTests.swift in Sources */,
 				064989461F5C99C7006E8BB3 /* Snapshot.swift in Sources */,
 			);

ChartsDemo/Objective-C/Demos/CombinedChartViewController.m

@@ -206,7 +206,7 @@ - (BarChartData *)generateBarData
     [set1 setColor:[UIColor colorWithRed:60/255.f green:220/255.f blue:78/255.f alpha:1.f]];
     set1.valueTextColor = [UIColor colorWithRed:60/255.f green:220/255.f blue:78/255.f alpha:1.f];
     set1.valueFont = [UIFont systemFontOfSize:10.f];
-    set1.axisDependency = AxisDependencyLeft;
+    set1.axisDependency = AxisDependencyRight;
 
     BarChartDataSet *set2 = [[BarChartDataSet alloc] initWithValues:entries2 label:@""];
     set2.stackLabels = @[@"Stack 1", @"Stack 2"];
@@ -216,7 +216,7 @@ - (BarChartData *)generateBarData
                     ];
     set2.valueTextColor = [UIColor colorWithRed:61/255.f green:165/255.f blue:255/255.f alpha:1.f];
     set2.valueFont = [UIFont systemFontOfSize:10.f];
-    set2.axisDependency = AxisDependencyLeft;
+    set2.axisDependency = AxisDependencyRight;
 
     float groupSpace = 0.06f;
     float barSpace = 0.02f; // x2 dataset

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

@@ -136,25 +136,31 @@ open class CombinedChartData: BarLineScatterCandleBubbleChartData
             {
                 _xMin = data.xMin
             }
-
-            if data.yMax > _leftAxisMax
-            {
-                _leftAxisMax = data.yMax
-            }
-
-            if data.yMin < _leftAxisMin
-            {
-                _leftAxisMin = data.yMin
-            }
-
-            if data.yMax > _rightAxisMax
-            {
-                _rightAxisMax = data.yMax
-            }
-
-            if data.yMin < _rightAxisMin
+
+            for dataset in sets
             {
-                _rightAxisMin = data.yMin
+                if dataset.axisDependency == .left
+                {
+                    if dataset.yMax > _leftAxisMax
+                    {
+                        _leftAxisMax = dataset.yMax
+                    }
+                    if dataset.yMin < _leftAxisMin
+                    {
+                        _leftAxisMin = dataset.yMin
+                    }
+                }
+                else
+                {
+                    if dataset.yMax > _rightAxisMax
+                    {
+                        _rightAxisMax = dataset.yMax
+                    }
+                    if dataset.yMin < _rightAxisMin
+                    {
+                        _rightAxisMin = dataset.yMin
+                    }
+                }
             }
         }
     }

Tests/Charts/CombinedChartTests.swift

@@ -0,0 +1,104 @@
+//
+//  CombinedChartTests.swift
+//  ChartsTests
+//
+//  Created by Xuan Liu on 14/10/2017.
+//
+
+import XCTest
+import FBSnapshotTestCase
+@testable import Charts
+
+class CombinedChartTests: FBSnapshotTestCase
+{
+    var chart: CombinedChartView!
+    var lineDataSet: LineChartDataSet!
+    var barDataSet: BarChartDataSet!
+
+    override func setUp()
+    {
+        super.setUp()
+
+        // Set to `true` to re-capture all snapshots
+        self.recordMode = false
+
+        // Sample data
+        let combinedData = CombinedChartData()
+        combinedData.barData = generateBarData()
+        combinedData.lineData = generateLineData()
+        chart = CombinedChartView(frame: CGRect(x: 0, y: 0, width: 480, height: 350))
+        chart.backgroundColor = NSUIColor.clear
+        chart.leftAxis.axisMinimum = 0.0
+        chart.rightAxis.axisMinimum = 0.0
+        chart.data = combinedData
+    }
+
+    func generateBarData() -> BarChartData
+    {
+        let values: [Double] = [8, 104, 81, 93, 52, 44, 97, 101, 75, 28,
+                                76, 25, 20, 13, 52, 44, 57, 23, 45, 91,
+                                99, 14, 84, 48, 40, 71, 106, 41, 45, 61]
+
+        var entries: [ChartDataEntry] = Array()
+
+        for (i, value) in values.enumerated()
+        {
+            entries.append(BarChartDataEntry(x: Double(i), y: value, icon: UIImage(named: "icon", in: Bundle(for: self.classForCoder), compatibleWith: nil)))
+        }
+
+        barDataSet = BarChartDataSet(values: entries, label: "Bar chart unit test data")
+        barDataSet.drawIconsEnabled = false
+
+        let data = BarChartData(dataSet: barDataSet)
+        data.barWidth = 0.85
+        return data
+    }
+
+    func generateLineData() -> LineChartData
+    {
+        let values: [Double] = [0, 254, 81, 93, 52, 44, 97, 101, 75, 28,
+                                76, 25, 20, 13, 52, 44, 57, 23, 45, 91,
+                                99, 14, 84, 48, 40, 71, 106, 41, 45, 61]
+
+        var entries: [ChartDataEntry] = Array()
+
+        for (i, value) in values.enumerated()
+        {
+            entries.append(ChartDataEntry(x: Double(i), y: value, icon: UIImage(named: "icon", in: Bundle(for: self.classForCoder), compatibleWith: nil)))
+        }
+
+        lineDataSet = LineChartDataSet(values: entries, label: "Line chart unit test data")
+        lineDataSet.drawIconsEnabled = false
+        return LineChartData(dataSet: lineDataSet)
+    }
+
+    override func tearDown()
+    {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+        super.tearDown()
+    }
+
+    func testDefaultAxisDependency()
+    {
+        FBSnapshotVerifyView(chart, identifier: Snapshot.identifier(UIScreen.main.bounds.size), tolerance: Snapshot.tolerance)
+    }
+
+    func testLeftRightAxisDependency()
+    {
+        lineDataSet.axisDependency = .left
+        barDataSet.axisDependency = .right
+        chart.data?.notifyDataChanged()
+        chart.notifyDataSetChanged()
+        FBSnapshotVerifyView(chart, identifier: Snapshot.identifier(UIScreen.main.bounds.size), tolerance: Snapshot.tolerance)
+    }
+
+    func testAllRightAxisDependency()
+    {
+        lineDataSet.axisDependency = .right
+        barDataSet.axisDependency = .right
+        chart.data?.notifyDataChanged()
+        chart.notifyDataSetChanged()
+        FBSnapshotVerifyView(chart, identifier: Snapshot.identifier(UIScreen.main.bounds.size), tolerance: Snapshot.tolerance)
+    }
+}
+