Question

I am trying to set up two charts similar to the AAPlot sample provided with Core Plot.
It basically consists of a stock chart, which is shown almost correctly and a second chart (volume chart), which should be placed directly below the stock chart. Both charts should share the same x axis.

Unfortunately the volume chart’s data is not being plotted in my app.

Even though I intensely compared the sample source code with mine, I do not find the source of my error.

Could you please point me to right direction?

This is my code:

- (void)configureChart
{
    self.graph = [[CPTXYGraph alloc] initWithFrame:self.hostView.bounds];
    self.hostView.hostedGraph = self.graph;
    self.graph.paddingLeft = 0.0f;
    self.graph.paddingTop = 0.0f;
    self.graph.paddingRight = 0.0f;
    self.graph.paddingBottom = 0.0f;
    self.graph.axisSet = nil;

    // 2 - Set up text style
    CPTMutableTextStyle *textStyle = [CPTMutableTextStyle textStyle];
    textStyle.color = [CPTColor grayColor];
    textStyle.fontName = @"Helvetica-Bold";
    textStyle.fontSize = 16.0f;

    // 3 - Configure title
    NSString *title = self.issue.company.companyName;
    _graph.title = title;    
    _graph.titleTextStyle = textStyle;
    _graph.titlePlotAreaFrameAnchor = CPTRectAnchorTop;    
    _graph.titleDisplacement = CGPointMake(0.0f, -12.0f);      

    // 4 - Set theme
    [self.graph applyTheme:[CPTTheme themeNamed:kCPTStocksTheme]];

    _graph.plotAreaFrame.cornerRadius  = 0.0f;
    CPTMutableLineStyle *borderLineStyle = [CPTMutableLineStyle lineStyle];
    borderLineStyle.lineColor           = [CPTColor whiteColor];
    borderLineStyle.lineWidth           = 2.0f;
    _graph.plotAreaFrame.borderLineStyle = borderLineStyle;


    // Axes
    CPTXYAxisSet *xyAxisSet        = (id)self.graph.axisSet;
    CPTXYAxis *xAxis               = xyAxisSet.xAxis;
    CPTMutableLineStyle *lineStyle = [xAxis.axisLineStyle mutableCopy];
    lineStyle.lineCap   = kCGLineCapButt;
    xAxis.axisLineStyle = lineStyle;
    xAxis.labelingPolicy = CPTAxisLabelingPolicyNone;

    CPTXYAxis *yAxis = xyAxisSet.yAxis;
    yAxis.axisLineStyle = nil;

    // OHLC plot
    CPTMutableLineStyle *whiteLineStyle = [CPTMutableLineStyle lineStyle];
    whiteLineStyle.lineColor = [CPTColor whiteColor];
    whiteLineStyle.lineWidth = 1.0f;
    CPTTradingRangePlot *ohlcPlot = [[CPTTradingRangePlot alloc] initWithFrame:self.graph.bounds];
    ohlcPlot.identifier = @"OHLC";
    ohlcPlot.lineStyle  = whiteLineStyle;
    CPTMutableTextStyle *whiteTextStyle = [CPTMutableTextStyle textStyle];
    whiteTextStyle.color    = [CPTColor whiteColor];
    whiteTextStyle.fontSize = 8.0;
    ohlcPlot.labelTextStyle = whiteTextStyle;
    ohlcPlot.labelOffset    = 5.0;
    ohlcPlot.stickLength    = 2.0f;
    ohlcPlot.dataSource     = self;
    ohlcPlot.plotStyle      = CPTTradingRangePlotStyleOHLC;
    [self.graph addPlot:ohlcPlot];

    // Add volume plot space
    CPTXYPlotSpace *volumePlotSpace = [[CPTXYPlotSpace alloc] init];
    volumePlotSpace.identifier = @"Volume";
    [_graph addPlotSpace:volumePlotSpace];

    CPTBarPlot *volumePlot = [CPTBarPlot tubularBarPlotWithColor:[CPTColor whiteColor] horizontalBars:NO];
    volumePlot.dataSource = self;

    lineStyle            = [volumePlot.lineStyle mutableCopy];
    lineStyle.lineColor  = [CPTColor whiteColor];
    volumePlot.lineStyle = lineStyle;

    volumePlot.fill       = nil;
    volumePlot.barWidth   = CPTDecimalFromFloat(1.0f);
    volumePlot.identifier = @"Volume Plot";
    [_graph addPlot:volumePlot toPlotSpace:volumePlotSpace];


    CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) self.graph.defaultPlotSpace;
    [plotSpace scaleToFitPlots:[self.graph allPlots]];
}

Answer 1

You never set the plot space ranges for the volume plot space. It still has the default x and y ranges of [0, 1].