Problems accessing 1:N relationship in entity

Question

I have entities: Bank,Section,Subsection,Set,Question. I am having problems accessing relationship "NSSet Subsection" in entity Section and getting the message "[UITableViewCell thesubsection]: unrecognized selector sent to instance" from this code in CRSectionVC.m which fills a tableview cell

- (NSArray *)allQuestions
{ 
NSSortDescriptor *division = [NSSortDescriptor sortDescriptorWithKey:@"subdivision"   ascending:YES];
return [_section2.thesubsection sortedArrayUsingDescriptors:@[division]];
}

I can however access the "NNSet section" relationship in Bank entity using this code

 NSSortDescriptor *division2 = [NSSortDescriptor sortDescriptorWithKey:@"division"  ascending:YES];
return [self.detailItem2.thesection sortedArrayUsingDescriptors:@[division2]];

_section2 is declared in CRSubsectionVC.h @property (strong, nonatomic) Section *section2;

The storyboard is 1. CRMasterViewController which displays ‘category’ attribute from Bank entity into a tableview,

Bank.h
@class Section;

@interface Bank : NSManagedObject

@property (nonatomic, retain) NSString * category;
@property (nonatomic, retain) NSSet *thesection;
@end

Bank.m
@implementation Bank

@dynamic category;
@dynamic thesection;

@end

When I tap a ‘category’ I segue and pass a Bank object to CRDetailViewController. I use following code:

NSSortDescriptor *division2 = [NSSortDescriptor sortDescriptorWithKey:@"division" ascending:YES]; return [self.detailItem2.thesection sortedArrayUsingDescriptors:@[division2]];

to fetch section relationship (NSSet *thesection) ‘division’ attribute from Bank into tableview.

Section.h

@class Bank, Subsection;

@interface Section : NSManagedObject

@property (nonatomic, retain) NSString * division;
@property (nonatomic, retain) Bank *bank;
@property (nonatomic, retain) NSSet *thesubsection;
@end

Section.m
@implementation Section

@dynamic division;
@dynamic bank;
@dynamic thesubsection;

@end

If I tap a ‘section’ ’ I segue and pass a Section object to CRSubsectionVC named _section2. When I try to access NSSet *thesubsection to get ‘subdivision’ attribute using code

NSSortDescriptor *division = [NSSortDescriptor sortDescriptorWithKey:@"subdivision"ascending:YES]; return [_section2.thesubsection sortedArrayUsingDescriptors:@[division]];

I get the error [UITableViewCell thesubsection]: unrecognized selector sent to instance. I cannot figure out why automated accessor ‘thesection’ works OK but not ‘thesubsection’ .

Subsection.h
@class Section, Set;

@interface Subsection : NSManagedObject

@property (nonatomic, retain) NSString * subdivision;
@property (nonatomic, retain) Section *section2;
@property (nonatomic, retain) NSSet *set;
@end

Subsection.m
@implementation Subsection

@dynamic subdivision;
@dynamic section2;
@dynamic set;

@end

Where is _section2 declared, and where do you assign a value to it? — Tom Harrington
_section2 is declared in CRSubsectionVC.h I've added how the storyboard interacts with entities to make problem clearer. — Lok

Lok Lok · Accepted Answer · 2014-11-19T02:09:04

Fixed the problem. A case of not copying code exactly from working template and understanding core data and table views.

Problems accessing 1:N relationship in entity

1 Answers