Core Plot: Exception 'Number of x and y values do not match' - objective-c

Question

I am unable to find a whole lot of information about this and I'm having zero luck in any way that I try to narrow down where this problem is coming from so I'm hoping somebody here can give me a bit more information and potential leads on why I might be getting this error.
I'm plotting a data set in real time as the data set is constantly increasing through me constantly receiving new data. When I receive new data I take the time i receive it as the x and the value itself as y, this is how I generate my points.
Full Error: Terminating app due to uncaught exception 'CPTException', reason: 'Number of x and y values do not match'
I have looked at my data set before the crash, I have made sure my point creation was never failing neither had anything wrong with them. I'm guessing at this point that is has something to do with my version of Scatter Plot, probably in the numberOfRecordsForPlot function. It doesn't seem to crash anywhere in that function however. The crash doesn't happen until usually 10+ seconds in, but again its not consistent, and before it crashes and am getting perfectly working plotting.
Any light people can shed on this is very much appreciated.
PS: If people want to see code, let me know what, anything non standard I have verified to be functioning to the best of my ability, and anything to do with Scatter Plot is fairly standard.
-(NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot
{
//Translation: The array with key of the top of the first selected parameter
NSInteger curCount = [self.graphParams count];
NSLog(#"Current Count: %d", curCount);
if ([plot.identifier isEqual:#"Sel_1"] && (curCount >= 1) ) {
if ([self.graphParams objectAtIndex: 0] != nil) {
//NSString *myText = ((UITableViewCell *)[self.graphParams objectAtIndex: 0]).textLabel.text;
//NSInteger myNum = [[self.graphData objectForKey: myText] count];
//return [[self.graphData objectForKey: myText] count];
//return [[self.graphData objectForKey: ((UITableViewCell *)[self.graphParams objectAtIndex: 0]).textLabel.text] count];
return [[self.graphData objectForKey: [self.graphParams objectAtIndex: 0]] count];
}
else
return 0;
}
else if ([plot.identifier isEqual:#"Sel_2"] && (curCount >= 2) ) {
if ([self.graphParams objectAtIndex: 1] != nil)
//return [[self.graphData objectForKey: ((UITableViewCell *)[self.graphParams objectAtIndex: 1]).textLabel.text] count];
return [[self.graphData objectForKey: [self.graphParams objectAtIndex: 1]] count];
else
return 0;
}
else if ([plot.identifier isEqual:#"Sel_3"] && (curCount >= 3) ) {
if ([self.graphParams objectAtIndex: 2] != nil)
//return [[self.graphData objectForKey: ((UITableViewCell *)[self.graphParams objectAtIndex: 2]).textLabel.text] count];
return [[self.graphData objectForKey: [self.graphParams objectAtIndex: 2]] count];
else
return 0;
}
return 0;
}
-(NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index
{
//Translation: The array with key of the top of the first selected parameter
NSValue *value = nil;
if ( [plot.identifier isEqual:#"Sel_1"] ) {
value = [[self.graphData objectForKey: [self.graphParams objectAtIndex:0]] objectAtIndex:index];
}
else if ( [plot.identifier isEqual:#"Sel_2"] ) {
value = [[self.graphData objectForKey: [self.graphParams objectAtIndex: 1]] objectAtIndex:index];
}
else if ( [plot.identifier isEqual:#"Sel_3"] ) {
value = [[self.graphData objectForKey: [self.graphParams objectAtIndex: 2]] objectAtIndex:index];
}
if (value != nil)
{
CGPoint point = [value CGPointValue];
if ( fieldEnum == CPTScatterPlotFieldX )
return [NSNumber numberWithFloat:point.x];
else if ( fieldEnum == CPTScatterPlotFieldY )
return [NSNumber numberWithFloat:point.y];
}
return [NSNumber numberWithFloat:0];
}
EDIT: Posted some scatter plot code where I think error may be coming from, but I dont know how useful this is to any of you. As always comment for additional requests and I'll be happy to provide anything that makes sense.

Answer 1

Make sure all access to the graphData dictionary and its contents are thread-safe. Core Plot does all of its datasource access and drawing on the main thread.
Always call -reloadData, -insertDataAtIndex:numberOfRecords:, and other Core Plot methods from the main thread.

Answer 2

I have also seen this. The exception happens when drawing the graph, not calling any of the data source functions.
Number of x and y values do not match
(
0 CoreFoundation 0x00007fff88f4df56 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff851cfd5e objc_exception_throw + 43
2 CoreFoundation 0x00007fff88f4dd8a +[NSException raise:format:arguments:] + 106
3 CoreFoundation 0x00007fff88f4dd14 +[NSException raise:format:] + 116
4 CorePlot 0x0000000100027c31 -[CPTScatterPlot renderAsVectorInContext:] + 561
5 CorePlot 0x000000010004dd50 -[CPTLayer drawInContext:] + 96
6 CorePlot 0x000000010001d023 -[CPTPlot drawInContext:] + 99
7 QuartzCore 0x00007fff8a673701 CABackingStoreUpdate_ + 3221
8 QuartzCore 0x00007fff8a672616 _ZN2CA5Layer8display_Ev + 1086
9 QuartzCore 0x00007fff8a66a4e6 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 560
10 QuartzCore 0x00007fff8a66949b _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 319
11 QuartzCore 0x00007fff8a669218 _ZN2CA11Transaction6commitEv + 274
12 QuartzCore 0x00007fff8a668819 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 63
13 CoreFoundation 0x00007fff88f0d8e7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
14 CoreFoundation 0x00007fff88f0d846 __CFRunLoopDoObservers + 374
15 CoreFoundation 0x00007fff88ee24a2 CFRunLoopRunSpecific + 258
16 HIToolbox 0x00007fff8d59c4d3 RunCurrentEventLoopInMode + 277
17 HIToolbox 0x00007fff8d5a3781 ReceiveNextEventCommon + 355
18 HIToolbox 0x00007fff8d5a360e BlockUntilNextEventMatchingListInMode + 62
19 AppKit 0x00007fff87df4e31 _DPSNextEvent + 659
20 AppKit 0x00007fff87df4735 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 135
21 AppKit 0x00007fff87df1071 -[NSApplication run] + 470
22 AppKit 0x00007fff8806d244 NSApplicationMain + 867
23 0x0000000100001a62 main + 34
24 0x0000000100001a34 start + 52
)
My app is also MultiThreaded, but I have made sure that [thePlot setDataNeedsReloading] is called in the main thread, and I have ensured that all my data source callbacks are being called in the main thread.
I'm sure that somehow, CorePlot is making two calls to get my data, and I'm adding more data in between those 2 calls, and CorePlot is confused.