Adding legend to CorePlot slice - ios

Question

I would like to be able to add a legend to a graph slice. How can I do this?
I tried to implement the following two methods but I don't think is right;
- (NSString *) legendTitleForPieChart:(CPTPieChart *)pieChart
recordIndex:(NSUInteger)idx{
return #"Legend";
}
- (NSAttributedString *) attributedLegendTitleForPieChart: (CPTPieChart *) pieChart
recordIndex: (NSUInteger) idxv{
return [[NSAttributedString alloc] initWithString:#"Attributed"];
}
Here is the official CorePlot protocol documentation:
https://core-plot.googlecode.com/hg/documentation/html/iOS/protocol_c_p_t_pie_chart_data_source-p.html#a6a85e1a9e613eb65267abfb8a884434a
EDIT: my code
// .h
#interface MyViewController : UIViewController<CPTPlotSpaceDelegate,CPTPieChartDelegate,CPTLegendDelegate,CPTPlotDataSource>
- (void) initializeAll;
- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil data:(NSMutableArray*)dataPoints;
// .m
#import “MyViewController.h"
#import <QuartzCore/QuartzCore.h>
#interface MyViewController ()
#property (weak, nonatomic) IBOutlet CPTGraphHostingView * pieChartgraphHostView;
#property (strong, nonatomic) CPTGraph* pieChartGraph;
#property (strong, nonatomic) CPTPieChart* pieChart;
#end
#implementation MyViewController
#synthesize data;
#synthesize pieChart, pieChartGraph;
- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil data:(NSMutableArray*)dataPoints{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.data = dataPoints;
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
[self initializeGraph];
[self updateViewData];
[self configureChart];
}
- (void) initializeGraph{
if (self.data == nil) {
NSLog(#"Error, should not use this without assigning data");
}
// Create a CPTGraph object and add to hostView
self.graph = [[CPTXYGraph alloc] initWithFrame:self.graphHostView.bounds];
self.graphHostView.hostedGraph = self.graph;
////////////////////
CPTMutableTextStyle *titleStyle = [CPTMutableTextStyle textStyle];
titleStyle.color = [CPTColor blackColor];
titleStyle.fontName = #"Helvetica";
titleStyle.fontSize = 12.0f;
// Axes
// Label x axis with a fixed interval policy
CPTXYAxisSet *axisSet = (CPTXYAxisSet *)self.graph.axisSet;
CPTXYAxis *x = axisSet.xAxis;
x.separateLayers = NO;
x.title = #"X Axis";
x.titleTextStyle = titleStyle;
x.delegate = self;
CPTXYAxis *y = axisSet.yAxis;
y.labelingPolicy = CPTAxisLabelingPolicyAutomatic;
y.separateLayers = YES;
y.majorTickLocations = [NSSet setWithObjects:
[NSDecimalNumber numberWithDouble:0],
[NSDecimalNumber numberWithDouble:300],
nil];
y.title = #"Y Axis";
y.titleTextStyle = titleStyle;
y.delegate = self;
CPTFill *whitebandFill = [CPTFill fillWithColor:[[CPTColor whiteColor] colorWithAlphaComponent:0.5]];
CPTFill *greenbandFill = [CPTFill fillWithColor:[[CPTColor greenColor] colorWithAlphaComponent:0.5]];
CPTFill *redbandFill = [CPTFill fillWithColor:[[CPTColor redColor] colorWithAlphaComponent:0.75]];
[y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocationDecimal:CPTDecimalFromDouble(0.0) lengthDecimal:CPTDecimalFromDouble(500.0)] fill:whitebandFill]];
[y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocationDecimal:CPTDecimalFromDouble(500.0) lengthDecimal:CPTDecimalFromDouble(750.0)] fill:greenbandFill]];
[y addBackgroundLimitBand:[CPTLimitBand limitBandWithRange:[CPTPlotRange plotRangeWithLocationDecimal:CPTDecimalFromDouble(750.0) lengthDecimal:CPTDecimalFromDouble(1024.0)] fill:redbandFill]];
// Add the y2 axis to the axis set
self.graph.axisSet.axes = #[x, y];
/////////////////////
// Get the (default) plotspace from the graph so we can set its x/y ranges
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) self.graph.defaultPlotSpace;
// Note that these CPTPlotRange are defined by START and LENGTH (not START and END) !!
[plotSpace setYRange: [CPTPlotRange plotRangeWithLocation:[NSNumber numberWithInt:0] length:[NSNumber numberWithInt:1024]]];
NSLog(#"creating x range for %lu data points", (unsigned long)[self.data count]);
[plotSpace setXRange: [CPTPlotRange plotRangeWithLocation:[NSNumber numberWithInt:0] length:[NSNumber numberWithInt:[self.data count]]]];
// Create the plot (we do not define actual x/y values yet, these will be supplied by the datasource...)
self.plot = [[CPTScatterPlot alloc] initWithFrame:CGRectZero];
// Let's keep it simple and let this class act as datasource (therefore we implemtn <CPTPlotDataSource>)
self.plot.dataSource = self;
self.plot.delegate = self;
// Finally, add the created plot to the default plot space of the CPTGraph object we created before
[self.graph addPlot:self.plot toPlotSpace:self.graph.defaultPlotSpace];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)configureChart {
// 1 - Get reference to graph
pieChartGraph = [[CPTXYGraph alloc] initWithFrame:self.pieChartgraphHostView.bounds];
self.pieChartgraphHostView.hostedGraph = pieChartGraph;
pieChartGraph.plotAreaFrame.masksToBorder = NO;
pieChartGraph.axisSet = nil;
pieChart.title = #"My pie chart";
// 2 - Create chart
pieChart = [[CPTPieChart alloc] init];
pieChart.dataSource = self;
pieChart.delegate = self;
pieChart.pieRadius = (self.pieChartgraphHostView.bounds.size.height * 0.9) / 2;
pieChartGraph.delegate = self;
pieChart.identifier = pieChartGraph.title;
pieChart.startAngle = CPTFloat(M_PI_4);
pieChart.sliceDirection = CPTPieDirectionClockwise;
pieChart.borderLineStyle = [CPTLineStyle lineStyle];
// 3 - Create gradient
CPTGradient *overlayGradient = [[CPTGradient alloc] init];
overlayGradient.gradientType = CPTGradientTypeRadial;
overlayGradient = [overlayGradient addColorStop:[[CPTColor blackColor] colorWithAlphaComponent:0.0] atPosition:0.9];
overlayGradient = [overlayGradient addColorStop:[[CPTColor blackColor] colorWithAlphaComponent:0.4] atPosition:1.0];
pieChart.overlayFill = [CPTFill fillWithGradient:overlayGradient];
// 4 - Add chart to graph
pieChart.pieRadius = pieChart.pieRadius / 2.3;
[pieChartGraph addPlot:pieChart];
self.dataForChart = [#[#20.0, #30.0, #25.0, #25.0] mutableCopy];
}
-(void)setRoundedView:(UIView *)roundedView toDiameter:(float)newSize;
{
CGPoint saveCenter = roundedView.center;
CGRect newFrame = CGRectMake(roundedView.frame.origin.x, roundedView.frame.origin.y, newSize, newSize);
roundedView.frame = newFrame;
roundedView.layer.cornerRadius = newSize / 2.0;
roundedView.center = saveCenter;
}
-(void)configureLegend {
// 1 - Get graph instance
CPTGraph *graph = self.graphHostView.hostedGraph;
// 2 - Create legend
CPTLegend *theLegend = [CPTLegend legendWithGraph:graph];
// 3 - Configure legen
theLegend.numberOfColumns = 1;
theLegend.fill = [CPTFill fillWithColor:[CPTColor whiteColor]];
theLegend.borderLineStyle = [CPTLineStyle lineStyle];
theLegend.cornerRadius = 5.0;
// 4 - Add legend to graph
graph.legend = theLegend;
graph.legendAnchor = CPTRectAnchorRight;
CGFloat legendPadding = -(self.view.bounds.size.width / 8);
graph.legendDisplacement = CGPointMake(legendPadding, 0.0);
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
#pragma mark -
#pragma mark Plot Data Source Methods
- (NSString *) legendTitleForPieChart:(CPTPieChart *)pieChart
recordIndex:(NSUInteger)idx{
return #"Legend";
}
/**
- (NSAttributedString *) attributedLegendTitleForPieChart: (CPTPieChart *) pieChart
recordIndex: (NSUInteger) idxv{
return [[NSAttributedString alloc] initWithString:#"Attributed"];
}**/
-(NSAttributedString *)attributedLegendTitleForPieChart:(CPTPieChart *)pieChart recordIndex:(NSUInteger)index
{
#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
UIColor *sliceColor = [CPTPieChart defaultPieSliceColorForIndex:index].uiColor;
UIFont *labelFont = [UIFont fontWithName:#"Helvetica" size:12.0 * CPTFloat(0.5)];
#else
NSColor *sliceColor = [CPTPieChart defaultPieSliceColorForIndex:index].nsColor;
NSFont *labelFont = [NSFont fontWithName:#"Helvetica" size:12.0 * CPTFloat(0.5)];
#endif
NSMutableAttributedString *title = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:#"Pie Slice %lu", (unsigned long)index]];
[title addAttribute:NSForegroundColorAttributeName
value:sliceColor
range:NSMakeRange(4, 5)];
[title addAttribute:NSFontAttributeName
value:labelFont
range:NSMakeRange(0, title.length)];
return title;
}
#end
Title, legend and labels won't show.

Answer 1

You only need one of those methods. Use the attributed title if you need styled text like in the example image, otherwise either method will work. These methods should be implemented in the plot's datasource.