Core Plot line not showing up - ios

Question

I have created a simple implementation of the CorePlot framework. The chart shows up fine, but there is no line plotted. I have tried logging out my sample values and indeed do have data. Any and all input on why the line of plotted data does not show up would be appreciated!
Header File:
#import <UIKit/UIKit.h>
#import "PresentedViewControllerDelegate.h"
#import "CorePlot-CocoaTouch.h"
#define NUM_SAMPLES 30
#interface DeviceDetailModal : UIViewController <PresentedViewControllerDelegate, UIWebViewDelegate, UITableViewDataSource, UITableViewDelegate, CPTPlotDataSource>{
CPTXYGraph *graph;
NSMutableArray *samples;
double xxx[NUM_SAMPLES];
double yyy1[NUM_SAMPLES];
}
#property (weak, nonatomic) IBOutlet UITableView *tableView;
#property (nonatomic, weak) id <PresentedViewControllerDelegate> delegate;
#end
Main File
#import <Foundation/Foundation.h>
#import "DeviceDetailModal.h"
#import "DetailCell.h"
#import "CorePlot-CocoaTouch.h"
#define START_POINT 0 // Start at origin
#define END_POINT 15.0 // TODO time is 15 seconds
#define X_VAL #"X_VAL"
#define Y_VAL #"Y_VAL"
#implementation DeviceDetailModal
-(void)viewDidLoad{
UIBarButtonItem *closeButton = [[UIBarButtonItem alloc] initWithTitle:#"Close" style:UIBarButtonItemStylePlain target:self action:#selector(closeView)];
self.navigationItem.leftBarButtonItem = closeButton;
[[UIBarButtonItem appearance] setTintColor:[UIColor lightGrayColor]];
[[UINavigationBar appearance] setBarTintColor:[UIColor blackColor]];
self.tableView.layer.cornerRadius = 10.0;
self.tableView.layer.borderWidth = 0.7;
self.tableView.layer.borderColor = [UIColor whiteColor].CGColor;
[self generateDataSamples];
NSNumber *xAxisStart = [NSNumber numberWithDouble:START_POINT];
NSNumber *xAxisLength = [NSNumber numberWithDouble:END_POINT - START_POINT];
double maxY = [[samples valueForKeyPath:#"#max.Y_VAL"] doubleValue];
NSNumber *yAxisStart = [NSNumber numberWithDouble:-maxY];
NSNumber *yAxisLength = [NSNumber numberWithDouble:2 *maxY];
CGRect hostingRect = CGRectMake(20, 330, 335, 347);
CPTGraphHostingView *hostingView = [[CPTGraphHostingView alloc] initWithFrame:hostingRect];
[self.view addSubview:hostingView];
graph = [[CPTXYGraph alloc] initWithFrame:hostingView.bounds];
hostingView.hostedGraph = graph;
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;
plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:xAxisStart
length:xAxisLength];
plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:yAxisStart
length:yAxisLength];
CPTScatterPlot *dataSourceLinePlot = [[CPTScatterPlot alloc] init];
dataSourceLinePlot.delegate = self;
// LINE STYLE
CPTMutableLineStyle *mainPlotLineStyle = [[dataSourceLinePlot dataLineStyle] mutableCopy];
[mainPlotLineStyle setLineWidth:2.0f];
[mainPlotLineStyle setLineColor:[CPTColor colorWithCGColor:[[UIColor whiteColor] CGColor]]];
[dataSourceLinePlot setDataLineStyle:mainPlotLineStyle];
// AXIS STYLE
CPTXYAxisSet *axisSet = (CPTXYAxisSet *)[graph axisSet];
CPTXYAxis *xAxis = [axisSet xAxis];
CPTXYAxis *yAxis = [axisSet yAxis];
CPTMutableLineStyle *axisLineStyle = [CPTMutableLineStyle lineStyle];
[axisLineStyle setLineWidth:1];
[axisLineStyle setLineColor:[CPTColor colorWithCGColor:[[UIColor whiteColor] CGColor]]];
[xAxis setAxisLineStyle:axisLineStyle];
[xAxis setMajorTickLineStyle:axisLineStyle];
[yAxis setAxisLineStyle:axisLineStyle];
[yAxis setMajorTickLineStyle:axisLineStyle];
[graph addPlot:dataSourceLinePlot];
NSLog(#"PLOT: %#",dataSourceLinePlot);
[graph reloadData];
}
-(void)generateDataSamples{
double length = (END_POINT - START_POINT);
double delta = length / (NUM_SAMPLES -1);
samples = [[NSMutableArray alloc] initWithCapacity:NUM_SAMPLES];
for (int i = 0; i < NUM_SAMPLES; i++) {
double x = START_POINT + (delta * i);
//X^2
double y = x * x;
NSDictionary *sample = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:x],X_VAL,
[NSNumber numberWithDouble:y],Y_VAL,
nil];
NSLog(#"SAMPLE: %#", sample);
[samples addObject:sample];
}
[graph reloadData];
}
-(NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot{
return NUM_SAMPLES;
}
-(NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index{
NSDictionary *sample = [samples objectAtIndex:index];
if (fieldEnum == CPTScatterPlotFieldX) {
return [sample valueForKey:X_VAL];
}else{
return [sample valueForKey:Y_VAL];
}
}

Answer 1

Found the problem! The data source for the plot was not set, I had to do:
dataSourceLinePlot.dataSource = self;
I found this out when my numberOfRecordsPerPlot method was never being called.

Answer 2

The default background fill is white and it doesn't look like you've changed it. The plot line is drawn with a white color so it doesn't show up on the white background. Try using the default line style or this:
mainPlotLineStyle.lineColor = [CPTColor blackColor];