Graph disappears in core plot - ios

Question

In my app I am using core plot. Everything is fine as below
.
On pressing next or prev button, core plot shows values of next or previous 7 days. When I press the button many times say 142 times, graph disappears and core plot only shows x and y labels as shown below..
And on tapping more app crashes. How can I fix my issue? Please help. Also in the debug area it shows
malloc: * mach_vm_map(size=8388608) failed (error code=3)
* error: can't allocate region securely
*** set a breakpoint in malloc_error_break to debug
It also gives bad access at
I don't know where my issue is.My code for generating graph is...
- (void)generateLayout
{
//Create graph from theme
self.graph = [[CPTXYGraph alloc] initWithFrame:CGRectZero];
CPTTheme *theme = [CPTTheme themeNamed:kCPTPlainWhiteTheme];
self.graph = (CPTXYGraph *)[theme newGraph];
//graph.fill = [CPTFill fillWithColor:[CPTColor clearColor]];
self.graph.plotAreaFrame.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:183.0/255.0 green:206.0/255.0 blue:227.0/255.0 alpha:1.0]];
//[graph applyTheme:[CPTTheme themeNamed:kCPTDarkGradientTheme]];
self.hostedGraph = self.graph;
self.graph.plotAreaFrame.masksToBorder = NO;
self.graph.paddingLeft = 0.0f;
self.graph.paddingTop = 0.0f;
self.graph.paddingRight = 0.0f;
self.graph.paddingBottom = 0.0f;
CPTMutableLineStyle *borderLineStyle = [CPTMutableLineStyle lineStyle];
borderLineStyle.lineColor = [CPTColor clearColor];
borderLineStyle.lineWidth = 2.0f;
self.graph.plotAreaFrame.borderLineStyle = borderLineStyle;
self.graph.plotAreaFrame.paddingTop = 10.0;
self.graph.plotAreaFrame.paddingRight = 10.0;
self.graph.plotAreaFrame.paddingBottom = 30.0;
self.graph.plotAreaFrame.paddingLeft = 50.0;
//Add plot space
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)self.graph.defaultPlotSpace;
plotSpace.delegate = self;
/////////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////// Here We Can Set The Range Of Y Axis////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////
plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(0) length:CPTDecimalFromInt(greaterGlass * sets.count)];
//plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0.0) length:CPTDecimalFromFloat(greaterGlass * sets.count)];
plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(-1)
length:CPTDecimalFromInt(8)];
//Grid line styles
CPTMutableLineStyle *majorGridLineStyle = [CPTMutableLineStyle lineStyle];
majorGridLineStyle.lineWidth = 2.75;
majorGridLineStyle.lineColor = [[CPTColor colorWithComponentRed:113.0/255.0 green:91.0/255.0 blue:84.0/255.0 alpha:1.0] colorWithAlphaComponent:1.0];
CPTMutableLineStyle *minorGridLineStyle = [CPTMutableLineStyle lineStyle];
minorGridLineStyle.lineWidth = 0.50;
minorGridLineStyle.lineColor = [[CPTColor whiteColor] colorWithAlphaComponent:0.1];
majorGridLineStyle.dashPattern = [NSArray arrayWithObjects:[NSNumber numberWithInteger:1], [NSNumber numberWithInteger:5], nil];
//Axes
CPTXYAxisSet *axisSet = (CPTXYAxisSet *)self.graph.axisSet;
//X axis
CPTXYAxis *x = axisSet.xAxis;
x.orthogonalCoordinateDecimal = CPTDecimalFromInt(0);
x.majorIntervalLength = CPTDecimalFromInt(1);
x.minorTicksPerInterval = 0;
x.labelingPolicy = CPTAxisLabelingPolicyNone;
x.majorGridLineStyle = majorGridLineStyle;
x.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0];
//X labels
int labelLocations = 0;
//NSMutableArray *customXLabels = [NSMutableArray array];
NSMutableArray *customXLabels = [NSMutableArray arrayWithCapacity:[dates count]];
//for (NSString *day in dates)
for(int couter=0; couter<[dates count]; couter++)
{
NSString *day = [NSString stringWithFormat:#"%#",[dates objectAtIndex:couter]];
CPTAxisLabel *newLabel = [[CPTAxisLabel alloc] initWithText:day textStyle:x.labelTextStyle];
newLabel.tickLocation = [[NSNumber numberWithInt:labelLocations] decimalValue];
newLabel.offset = x.labelOffset + x.majorTickLength;
//newLabel.rotation = M_PI / 4;
[customXLabels addObject:newLabel];
labelLocations++;
[newLabel release];
}
x.axisLabels = [NSSet setWithArray:customXLabels];
//Y axis
CPTXYAxis *y = axisSet.yAxis;
CGRect frame = CGRectMake(0, 0, 50, 30);
UILabel *label = [[UILabel alloc] initWithFrame:frame] ;
label.font = [UIFont fontWithName:#"ComicSansMS-Bold" size:12.0];
label.textAlignment = NSTextAlignmentCenter;
label.text = #"Number of Glasses";
y.title = label.text;
y.titleOffset = 50.0f;
y.labelingPolicy = CPTAxisLabelingPolicyAutomatic;
y.majorGridLineStyle = majorGridLineStyle;
y.minorGridLineStyle = minorGridLineStyle;
y.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0];
//Create a bar line style
CPTMutableLineStyle *barLineStyle = [[[CPTMutableLineStyle alloc] init] autorelease];
barLineStyle.lineWidth = 1.0;
barLineStyle.lineColor = [CPTColor whiteColor];
CPTMutableTextStyle *whiteTextStyle = [CPTMutableTextStyle textStyle];
whiteTextStyle.color = [CPTColor whiteColor];
//Plot
BOOL firstPlot = YES;
for (NSString *set in [[sets allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)]) {
//UIColor *myColor = [UIColor colorWithRed:87.0/255.0 green:181.0/255.0 blue:229.0/255.0 alpha:1.0];
//CPTColor *mineColor = [CPTColor colorWithComponentRed:160 green:97 blue:5 alpha:1];
CPTBarPlot *plot = [CPTBarPlot tubularBarPlotWithColor:[CPTColor blueColor] horizontalBars:NO];
plot.lineStyle = barLineStyle;
CGColorRef color = ((UIColor *)[sets objectForKey:set]).CGColor;
//plot.fill = [CPTFill fillWithColor:[CPTColor colorWithCGColor:color]];
plot.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:111.0/255.0 green:164.0/255.0 blue:205.0/255.0 alpha:1.0]];
if (firstPlot) {
plot.barBasesVary = NO;
firstPlot = NO;
} else {
plot.barBasesVary = YES;
}
plot.barWidth = CPTDecimalFromFloat(0.5f);
plot.barsAreHorizontal = NO;
plot.dataSource = self;
plot.identifier = set;
[self.graph addPlot:plot toPlotSpace:plotSpace];
}
}