Core-plot label not display on top of each bar column

Question

Hi everyone,

I am new with Core-plot. I would like to add label about the number on each of bar column on CPBarPlot. I knew that I must implement this method of CPBarPlotDataSource delegate:

 -(CPTextLayer *)barLabelForBarPlot:(CPBarPlot *)barPlot recordIndex:
     (NSUInteger)index;

But even I implemented that method, nothing happen, the graph displays without label on top of each bar. Do I miss something?

This is my code:

- (void) constructBarChart {
 //create bar chart from theme
 barChart = [[CPXYGraph alloc] initWithFrame:CGRectZero];
 CPTheme *theme = [CPTheme themeNamed:kCPPlainWhiteTheme];
 [barChart applyTheme:theme];
 hostView.hostedLayer = barChart;
 barChart.plotAreaFrame.masksToBorder = NO;

 barChart.paddingTop = 30.0;
 barChart.paddingBottom = 30.0;
 barChart.paddingLeft = 30.0;
 barChart.paddingRight = 30.0;


 // setup plot space
 CPXYPlotSpace *plotSpace = (CPXYPlotSpace*)barChart.defaultPlotSpace;
 plotSpace.allowsUserInteraction = YES;
 plotSpace.delegate = self;
 plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromFloat(10.0f)];
    plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromFloat(10.0f)];
 plotSpace.globalXRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromFloat(20.0f)];
 plotSpace.globalYRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromFloat(20.0f)];


 // Grid line styles
    CPLineStyle *majorGridLineStyle = [CPLineStyle lineStyle];
    majorGridLineStyle.lineWidth = 0.75;
    majorGridLineStyle.lineColor = [[CPColor colorWithGenericGray:0.2]
         colorWithAlphaComponent:0.75];

    CPLineStyle *minorGridLineStyle = [CPLineStyle lineStyle];
    minorGridLineStyle.lineWidth = 0.25;
    minorGridLineStyle.lineColor = [[CPColor whiteColor]
         colorWithAlphaComponent:0.1];

    CPLineStyle *redLineStyle = [CPLineStyle lineStyle];
    redLineStyle.lineWidth = 10.0;
    redLineStyle.lineColor = [[CPColor redColor]
         colorWithAlphaComponent:0.5]; 


 //Axis
 CPXYAxisSet *axisSet = (CPXYAxisSet*)barChart.axisSet;
 CPXYAxis *x = axisSet.xAxis;
 CPLineStyle *lineStyle = [CPLineStyle lineStyle];
 lineStyle.lineColor = [CPColor blackColor];
 x.axisLineStyle = lineStyle;
 x.majorIntervalLength = CPDecimalFromString(@"5");
 x.minorTicksPerInterval = 4;


 CPXYAxis *y = axisSet.yAxis;
 y.axisLineStyle = lineStyle;
 y.majorIntervalLength = CPDecimalFromString(@"1");
 y.majorGridLineStyle = majorGridLineStyle;
 y.isFloatingAxis = YES;


 CPBarPlot *barPlot = [CPBarPlot tubularBarPlotWithColor:[CPColor redColor] horizontalBars:NO];
 barPlot.baseValue = CPDecimalFromString(@"0");
 barPlot.dataSource = self;
 barPlot.delegate = self;
 barPlot.identifier = @"Bar Plot 1";
 [barChart addPlot:barPlot toPlotSpace: plotSpace];
}

- (NSUInteger) numberOfRecordsForPlot:(CPPlot*)plot {
 if ([plot isKindOfClass:[CPBarPlot class]]) {
  return 16;
 } else {
  return [dataGraph count];
 }
}

- (NSNumber *)numberForPlot: (CPPlot*) plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger) index {
 NSDecimalNumber *num = nil;
 if ([plot isKindOfClass:[CPBarPlot class]]) {
  switch (fieldEnum) {
   case CPBarPlotFieldBarLocation:
    num = (NSDecimalNumber *)[NSDecimalNumber numberWithUnsignedInteger:index];
    break;
   case CPBarPlotFieldBarLength:
    num = (NSDecimalNumber *) [NSDecimalNumber numberWithUnsignedInteger:(index + 1)];
    break;
  }
 } else {
  num = [[dataGraph objectAtIndex:index] valueForKey:(fieldEnum == CPScatterPlotFieldX ? @"x" : @"y")];
 }
 return num;
}

#pragma mark -
#pragma mark Plot Space Delegate Methods 

-(CGPoint)plotSpace:(CPPlotSpace *)space willDisplaceBy:(CGPoint)proposedDisplacementVector {
 CGPoint result = CGPointMake(proposedDisplacementVector.x, 0.0);
 return result;
}

#pragma mark -
#pragma mark Bar Plot Delegate Methods

- (CPTextLayer *) barLabelForBarPlot:(CPBarPlot *) barPlot recordIndex:(NSUInteger) index {
 CPTextLayer *textLayer = [[CPTextLayer alloc] initWithText:[NSString stringWithFormat:@"%d", index+1]];
 return textLayer;
}

Any help would be appreciated.

Thanks

Answer 1

The labeling method changed recently. It's just a name change; it works the same as before. The new declaration is:

-(CPLayer *)dataLabelForPlot:(CPPlot *)plot recordIndex:(NSUInteger)index;

Also, this method should return autoreleased objects to prevent memory leaks.