Question

https://github.com/lokming/QuestionBank

我有实体：银行，部门，分部，集，问题。我在访问关系时遇到问题＆＃34; NSSet Subsection＆＃34;在实体部分并获取消息＆＃34; [UITableViewCell thesubsection]：无法识别的选择器发送到实例＆＃34;从这段代码在CRSectionVC.m中填充tableview单元格

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

然而，我可以访问＆＃34; NNSet部分＆＃34;使用此代码的银行实体中的关系

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

_section2在CRSubsectionVC.h中声明 @property（强，非原子）Section * section2;

故事板是 1. CRMasterViewController，它将Bank实体的“category”属性显示为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

当我点击“类别”时，我会将一个Bank对象传递给CRDetailViewController。我使用以下代码：

NSSortDescriptor * division2 = [NSSortDescriptor sortDescriptorWithKey：@＆＃34; division＆＃34;升序：YES]; return [self.detailItem2.thesection sortedArrayUsingDescriptors：@ [division2]];

从Bank获取段关系（NSSet * thisction）'division'属性到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

如果我点击'section''我会将一个Section对象传递给名为_section2的CRSubsectionVC。当我尝试访问NSSet * thesubsection以使用代码
获取'subdivision'属性时
NSSortDescriptor * division = [NSSortDescriptor sortDescriptorWithKey：@＆＃34; subdivision＆＃34; ascending：YES]; return [_section2.thesubsection sortedArrayUsingDescriptors：@ [division]];

我收到错误[UITableViewCell thesubsection]：无法识别的选择器发送到实例。我无法弄清楚为什么自动访问器'thisction'工作正常而不是'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

Answer 1

修正了问题。这种情况不是完全从工作模板中复制代码并理解核心数据和表视图。

在实体中访问1：N关系的问题

1 个答案: