Encapsulating data and CPTScatterPlot object with delegates into one class - core-plot

Question

I am trying to find a way to encapsulate the data for a plot and the delegate functions in one class. This will make it much simpler to create multiple plots dynamically based on the number of data sets that I acquire.
To do so, I created a class that includes the x, y data points and CPTScatterPlot object, as well as the standard delegate functions, which are now class methods that access the internal data.
When the object is instantiated, the idea is to pass it the data and the graph object, and the constructor makes "self" the data source.
Here is the code:
// DataScatterPlot.h
#import <Foundation/Foundation.h>
#import "CorePlot-CocoaTouch.h"
#interface DataScatterPlot : NSObject <CPTScatterPlotDataSource>
#property (nonatomic, strong) CPTScatterPlot *CPTScatterPlotObj;
#property (nonatomic, strong) NSMutableArray *x;
#property (nonatomic, strong) NSMutableArray *y;
- (id) initWithGraph: (CPTXYGraph*) graph DataX: (NSMutableArray*) x andDataY: (NSMutableArray*) y;
#end
// DataScatterPlot.m
#import "DataScatterPlot.h"
#implementation DataScatterPlot
-(id) initWithGraph: (CPTXYGraph *)graph DataX:(NSMutableArray *)dataX andDataY:(NSMutableArray *)dataY {
self = [super init];
if ( self != nil ) {
self.CPTScatterPlotObj = [[CPTScatterPlot alloc] init];
self.x = dataX;
self.y = dataY;
self.CPTScatterPlotObj.dataSource = (id<CPTScatterPlotDataSource>) self;
[graph addPlot:self.CPTScatterPlotObj];
}
return self;
}
// Delegate method that returns the number of points on the plot
-(NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot
{
NSLog(#"The count is %lu", (unsigned long)[self.x count]);
return [self.x count];
}
// Delegate method that returns a single X or Y value for a given plot.
-(NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index
{
// For Sigmoid
NSNumber *dataX = [self.x objectAtIndex:index];
NSNumber *dataY = [self.y objectAtIndex:index];
// FieldEnum determines if we return an X or Y value.
switch (fieldEnum) {
case CPTScatterPlotFieldX:
{
return dataX;
}
case CPTScatterPlotFieldY: // Y-Axis
{
return dataY;
}
default:
return [NSNumber numberWithFloat:0];
}
}
#end
When I run the code, I get an "unrecognized selector sent to instance" error, which seems it indicate it is looking for a method that does not exist within the object.
Is there something that I'm doing incorrectly?
Here is the error message:
2015-10-09 12:02:09.743 SigmoidWithCustomDataClass[1192:10285] -[__NSDictionaryI numberOfRecordsForPlot:]: unrecognized selector sent to instance 0x7f9a2bda7fb0
2015-10-09 12:02:10.550 SigmoidWithCustomDataClass[1192:10285] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI numberOfRecordsForPlot:]: unrecognized selector sent to instance 0x7f9a2bda7fb0'
*** First throw call stack:
(
0 CoreFoundation 0x000000010f697c65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010f330bb7 objc_exception_throw + 45
2 CoreFoundation 0x000000010f69f0ad -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3 CoreFoundation 0x000000010f5f513c ___forwarding___ + 988
4 CoreFoundation 0x000000010f5f4cd8 _CF_forwarding_prep_0 + 120
5 SigmoidWithCustomDataClass 0x000000010eaae44b -[CPTPlot reloadData] + 94
6 SigmoidWithCustomDataClass 0x000000010eaae289 -[CPTPlot drawInContext:] + 36
7 QuartzCore 0x000000010ec1b92b CABackingStoreUpdate_ + 2793
8 QuartzCore 0x000000010ed21933 ___ZN2CA5Layer8display_Ev_block_invoke + 59
9 QuartzCore 0x000000010ed217be _ZN2CA5Layer8display_Ev + 1478
10 QuartzCore 0x000000010ed164d9 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 301
11 QuartzCore 0x000000010ed16561 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 35
12 QuartzCore 0x000000010ec8286e _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 242
13 QuartzCore 0x000000010ec83a22 _ZN2CA11Transaction6commitEv + 462
14 UIKit 0x000000010fcd09ed -[UIApplication _reportMainSceneUpdateFinished:] + 44
15 UIKit 0x000000010fcd16b1 -[UIApplication _runWithMainScene:transitionContext:completion:] + 2648
16 UIKit 0x000000010fcd0095 -[UIApplication workspaceDidEndTransaction:] + 179
17 FrontBoardServices 0x0000000114bb75e5 __31-[FBSSerialQueue performAsync:]_block_invoke_2 + 21
18 CoreFoundation 0x000000010f5cb41c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
19 CoreFoundation 0x000000010f5c1165 __CFRunLoopDoBlocks + 341
20 CoreFoundation 0x000000010f5c0f25 __CFRunLoopRun + 2389
21 CoreFoundation 0x000000010f5c0366 CFRunLoopRunSpecific + 470
22 UIKit 0x000000010fccfb02 -[UIApplication _run] + 413
23 UIKit 0x000000010fcd28c0 UIApplicationMain + 1282
24 SigmoidWithCustomDataClass 0x000000010eaad71f main + 111
25 libdyld.dylib 0x0000000112474145 start + 1
26 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

The plot's datasource is a dictionary. Check the rest of your code and make sure you're not reassigning the datasource anywhere.