title: Core Plot 1.0 how to implement reloadData method?
body: <p>I asked this question yesterday and got some great help from Eric Skroch.  However, I am still a bit confused after looking over all the documentation on the Core Plot website along with some examples.  So I am going to post the code I have so far, and see if anyone can help me out some more.  Maybe it will be a bit easier for Eric to help as well.  My problem is that I need to remove a plot and then replace it with another in a tabbed app.  Eric and others have said to use the reloadData method.  But I don't see where I can use it in my code?  Here are my header and implementation files.</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  #import "CorePlot-CocoaTouch.h" 
  
  @interface GraphViewController : UIViewController &lt;CPTPlotDataSource&gt;
  
  @property (nonatomic, strong) CPTGraphHostingView *hostView;
  @property (nonatomic, strong) NSMutableArray *myData;
  @property (nonatomic) float XAXISMIN;
  @property (nonatomic) float XAXISMAX;
  @property (nonatomic) float YAXISMIN;
  @property (nonatomic) float YAXISMAX;
  @property (strong, nonatomic) IBOutlet UILabel *noGraph;
  
  @end
  </code></pre>
  
  <p>and</p>
  
  <pre><code>#import "GraphViewController.h"
  #import "MyVariables.h"  // a singleton class for my variables
  
  @interface GraphViewController ()
  
  @end
  
  @implementation GraphViewController
  
  @synthesize  hostView = _hostView;
  @synthesize myData = _myData;
  @synthesize XAXISMIN;
  @synthesize XAXISMAX;
  @synthesize YAXISMAX;
  @synthesize noGraph;
  @synthesize YAXISMIN;
  
  - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
  {
  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
  if (self) {
      // Custom initialization
  }
  return self;
  }
  
  - (void)viewWillAppear:(BOOL)animated
  {
  [super viewWillAppear:animated];
  [noGraph setText:@""];
  }
  
  - (void)viewDidAppear:(BOOL)animated
  {
  
  [super viewDidAppear:animated];
  MyVariables *sharedVariables2 = [MyVariables sharedVariables2];
  float a = [sharedVariables2.AA floatValue];
  MyVariables *sharedVariables3 = [MyVariables sharedVariables3];
  float b = [sharedVariables3.BB floatValue];    
  MyVariables *sharedVariables4 = [MyVariables sharedVariables4];
  float c = [sharedVariables4.CC floatValue];
  
  float d = (4.0f)*a*c;
  float e = (b*b);
  float f = (e - d);
  float g = sqrtf(f);
  float h = -b;
  float i = h + g;
  float ii = h - g;
  float j = i/(2*a);
  float k = ii/(2*a);
  
  // Define x max and min with answers to quad
  XAXISMIN = j - (5.0);
  XAXISMAX = k + (5.0);
  
  // Find range for the y axis  STILL NEEDS WORK!
  // maybe if statement for negatives
  float z = c - ((b*b)/((4.0f)*a));
  YAXISMAX = z + 10.0f;
  YAXISMIN = -z;
  
  float inc = (XAXISMAX - XAXISMIN) / 100.0f;
  float l = XAXISMIN;
  
  if ((isnan(g))  || (a == 0))
  { 
      [noGraph setText:@"This is not graphable"];
      [_hostView setHidden:YES];
  }
  else 
  {
      NSMutableArray *data = [NSMutableArray array];
  
      for (int i = 0; i &lt; 100; i ++)
      {
  
          float y = (a * (l*l)) + (b * l) + c;
  
          NSString *str4 = [NSString stringWithFormat:@"%.3f", l];
          NSString *str5 = [NSString stringWithFormat:@"%.3f", y];
  
          NSLog(@"Our X and Y are : %@, %@", str4, str5);
          [data addObject:[NSValue valueWithCGPoint:CGPointMake(l, y)]];
          l = l + inc;
  
  
      }
      self.myData = data;  // put that data array into the array you synthesized
      [self initPlot];   
  }
  }
  
  - (void)viewDidLoad
  {
  [super viewDidLoad];
  // Do any additional setup after loading the view.
  }
  
  - (void)viewDidUnload
  {   
  [self setNoGraph:nil];
  [super viewDidUnload];
  // Release any retained subviews of the main view.
  }
  
  - (void)viewWillDisappear:(BOOL)animated
  {
  [super viewWillDisappear:animated];
  
  }
  
  - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
  {
  return (interfaceOrientation == UIInterfaceOrientationPortrait);
  }
  
  - (NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot
  {
  return [_myData count];  
  }
  
  - (NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:  (NSUInteger)index
  {
  if ([plot.identifier isEqual:@"Your data"])
  {
      NSValue *value = [self.myData objectAtIndex:index];
      CGPoint point = [value CGPointValue];
  
      // FieldEnum determines if we return an X or Y value.
      if (fieldEnum == CPTScatterPlotFieldX) 
      {
          return [NSNumber numberWithFloat:point.x];
      }
      else    // Y-Axis
      {
          return [NSNumber numberWithFloat:point.y];
      }
  }
  return [NSNumber numberWithFloat:0];
  }
  
  - (void)initPlot
  {
  [self configureHost];
  [self configureGraph];
  [self configurePlots];
  [self configureAxes];
  
  }
  
  - (void)configureHost
  {
  self.hostView = [(CPTGraphHostingView *) [CPTGraphHostingView alloc] initWithFrame:self.view.bounds]; 
  self.hostView.allowPinchScaling = YES;
  [self.view addSubview:self.hostView];
  }
  
  - (void)configureGraph
  {
  // 1 - Create graph
  CPTGraph *graph = [[CPTXYGraph alloc] initWithFrame:self.hostView.bounds];
  self.hostView.hostedGraph = graph;
  
  
  // 2 - Set graph title
  NSString *title = @"Your Quadratic";
  graph.title = title;
  
  // 3 - Create and set text style
  CPTMutableTextStyle *titleStyle = [CPTMutableTextStyle textStyle];
  titleStyle.color = [CPTColor whiteColor];
  titleStyle.fontName = @"Helvetica-Bold";
  titleStyle.fontSize = 16.0f;
  graph.titleTextStyle = titleStyle;
  graph.titlePlotAreaFrameAnchor = CPTRectAnchorTop;
  graph.titleDisplacement = CGPointMake(0.0f, 10.0f);
  
  // 4 - Set padding for plot area
  [graph.plotAreaFrame setPaddingTop:30.0f];
  [graph.plotAreaFrame setPaddingRight:30.0f];
  [graph.plotAreaFrame setPaddingLeft:30.0f];
  [graph.plotAreaFrame setPaddingBottom:30.0f];
  
  // 5 - Enable use interaction for plot space
  CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;
  plotSpace.allowsUserInteraction = YES;
  }
  
  - (void)configurePlots
  {
  // 1 - Get graph and plot spaces and set axis
  CPTGraph *graph = self.hostView.hostedGraph;
  CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) graph.defaultPlotSpace;
  
  float xAxisMin = XAXISMIN;
  float xAxisMax = XAXISMAX;
  float yAxisMin = YAXISMIN;
  float yAxisMax = YAXISMAX;
  
  plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(xAxisMin) length:CPTDecimalFromFloat(xAxisMax - xAxisMin)];
  plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(yAxisMin) length:CPTDecimalFromFloat(yAxisMax - yAxisMin)];
  
  // 2 - Create the plot
  CPTScatterPlot *quadGraph = [[CPTScatterPlot alloc] init];
  quadGraph.dataSource = self;
  quadGraph.identifier = @"Your data";
  CPTColor *quadColor = [CPTColor blackColor];
  [graph addPlot:quadGraph toPlotSpace:plotSpace];
  
  // 4 - Create styles and symbols
  CPTMutableLineStyle *quadLineStyle = [quadGraph.dataLineStyle mutableCopy];
  quadLineStyle.lineWidth = 2.5;
  quadLineStyle.lineColor = quadColor;
  quadGraph.dataLineStyle = quadLineStyle;
  
  CPTMutableLineStyle *quadSymbolLineStyle = [CPTMutableLineStyle lineStyle];
  quadSymbolLineStyle.lineColor = quadColor;
  
  CPTPlotSymbol *quadSymbol = [CPTPlotSymbol ellipsePlotSymbol];
  quadSymbol.fill = [CPTFill fillWithColor:quadColor];
  quadSymbol.lineStyle = quadSymbolLineStyle;
  quadSymbol.size = CGSizeMake(6.0f, 6.0f);
  quadGraph.plotSymbol = quadSymbol;
  
  }
  
  - (void)configureAxes
  {
  // 1 - Create styles
  CPTMutableTextStyle *axisTitleStyle = [CPTMutableTextStyle textStyle];
  axisTitleStyle.color = [CPTColor whiteColor];
  axisTitleStyle.fontName = @"Helvetica-Bold";
  axisTitleStyle.fontSize = 12.0f;
  CPTMutableLineStyle *axisLineStyle = [CPTMutableLineStyle lineStyle];
  axisLineStyle.lineWidth = 2.0f;
  axisLineStyle.lineColor = [CPTColor whiteColor];
  CPTMutableTextStyle *axisTextStyle = [[CPTMutableTextStyle alloc] init];
  axisTextStyle.color = [CPTColor whiteColor];
  axisTextStyle.fontName = @"Helvetica-Bold";    
  axisTextStyle.fontSize = 11.0f;
  CPTMutableLineStyle *tickLineStyle = [CPTMutableLineStyle lineStyle];
  tickLineStyle.lineColor = [CPTColor whiteColor];
  tickLineStyle.lineWidth = 2.0f;
  CPTMutableLineStyle *gridLineStyle = [CPTMutableLineStyle lineStyle];
  tickLineStyle.lineColor = [CPTColor blackColor];
  tickLineStyle.lineWidth = 1.0f;
  
  // 2 - Get axis set
  CPTXYAxisSet *axisSet = (CPTXYAxisSet *) self.hostView.hostedGraph.axisSet;
  
  // 3 - Configure x-axis
  CPTAxis *x = axisSet.xAxis;
  x.title = @"X Axis"; 
  x.titleTextStyle = axisTitleStyle;    
  x.titleOffset = 1.0f;
  x.axisLineStyle = axisLineStyle;
  x.labelingPolicy = CPTAxisLabelingPolicyEqualDivisions; //CPTAxisLabelingPolicyNone;
  x.labelTextStyle = axisTextStyle;    
  x.majorTickLineStyle = axisLineStyle;
  x.majorTickLength = 4.0f;
  x.tickDirection = CPTSignPositive; //CPTSignNegative;
  
  // 4 - Configure y-axis
  CPTAxis *y = axisSet.yAxis;    
  y.title = @"Y Axis";
  y.titleTextStyle = axisTitleStyle;
  y.titleOffset = -40.0f;       
  y.axisLineStyle = axisLineStyle;
  y.majorGridLineStyle = gridLineStyle;
  y.labelingPolicy = CPTAxisLabelingPolicyEqualDivisions;
  y.labelTextStyle = axisTextStyle;    
  y.labelOffset = 16.0f;
  y.majorTickLineStyle = axisLineStyle;
  y.majorTickLength = 4.0f;
  y.minorTickLength = 2.0f;    
  y.tickDirection = CPTSignNegative;
  
  }
  
  @end
  </code></pre>
  
  <p>So I hope someone can let me know where to clear my data/plot so I only have one graph on the graph tab at a time.  Thanks so much in advance!</p>