NSManagedObject基类的无法识别的选择器 [英] Unrecognized selector for NSManagedObject base class

问题描述

我在实例上调用基类方法时遇到无法识别的选择器异常，无法看到问题所在。

我有一个对象调用Form如下：

  #import< Foundation / Foundation.h> 
 #import< CoreData / CoreData.h> 
 #importHPSDbBase.h
 
 @interface表单：HPSDbBase 
 
 @end 
  

Form的基类如下：

  #import< CoreData / CoreData.h> 
 
 @interface HPSDbBase：NSManagedObject 
 
 @property（nonatomic，retain）NSString * id; 
 @property（nonatomic，retain）NSString * json; 
 
  - （id）getJSONElement：（NSString *）key; 
 
 @end 
  

然后尝试在视图控制器中使用Form对象方法如下：

  HPSAppDelegate * appDelegate = [[UIApplication sharedApplication] delegate]; 
 
 NSError * error = nil 
 NSFetchRequest * request = [[NSFetchRequest alloc] init]; 
 
 [请求setEntity：[NSEntityDescription entityForName：@ForminManagedObjectContext：appDelegate.managedObjectContext]]; 
 
 NSArray * arrayOfForms = [appDelegate.managedObjectContext executeFetchRequest：request error：& error]; 
 
 for（int i = 0; i  {
 
 Form * dbForm = [arrayOfForms objectAtIndex：i]; 
 
 NSLog（@Form.json =％@，dbForm.json）; // this works 
 
 NSString * wwwww =（Form *）[dbForm getJSONElement：@test]; // exception here 
 
} 
  

例外是：

   -  [NSManagedObject getJSONElement：]：无法识别的选择器发送到实例0x8290940 
  

任何人都能看到我做错了什么？

感谢一百万！

EDIT 1

以下是HPSDbBase的实现：

  #importHPSDbBase.h
 
 @implementation HPSDbBase 
 
 @dynamic id; 
 @dynamic json; 
 
 
  - （id）getJSONElement：（NSString *）key 
 {
 NSData * jsonData = [[self json] dataUsingEncoding：NSUTF8StringEncoding]; 
 
 NSError * e = nil; 
 
 id jsonObject = [NSJSONSerialization JSONObjectWithData：jsonData options：NSJSONReadingMutableContainers error：& e]; 
 NSDictionary * jsonDictionary =（NSDictionary *）jsonObject; 
 
 id rc = [jsonDictionary objectForKey：key]; 
 
 return rc; 
} 
 
 @end 
  

解决方案>

我跟踪了问题。

我重命名了我的核心数据对象。我重命名了我可以看到的关于核心数据对象的名称的一切，但它显然是不够的。我删除了核心数据实体，然后用正确的名称重新创建了一个全新的实体，并开始工作。

I am getting an 'unrecognised selector' exception when calling a base-class method on an instance and can't see what the problem is.

I have an object called Form as follows:

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#import "HPSDbBase.h"

@interface Form : HPSDbBase

@end

The base class for Form looks like this:

#import <CoreData/CoreData.h>

@interface HPSDbBase : NSManagedObject

@property (nonatomic, retain) NSString * id;
@property (nonatomic, retain) NSString * json;

-(id)getJSONElement:(NSString*)key;

@end

I then try using the Form object within a view controller method as follows:

HPSAppDelegate* appDelegate = [[UIApplication sharedApplication] delegate];

NSError* error = nil;
NSFetchRequest * request = [[NSFetchRequest alloc] init];

[request setEntity:[NSEntityDescription entityForName:@"Form" inManagedObjectContext:appDelegate.managedObjectContext]];

NSArray* arrayOfForms = [appDelegate.managedObjectContext executeFetchRequest:request error:&error];

for (int i=0;i<arrayOfForms.count;i++)
{

    Form* dbForm = [arrayOfForms objectAtIndex:i];

    NSLog(@"Form.json=%@",dbForm.json); // this works

    NSString* wwwww = (Form*)[dbForm getJSONElement:@"test"]; // exception here

}

The exception is:

-[NSManagedObject getJSONElement:]: unrecognized selector sent to instance 0x8290940

Can anyone see what I'm doing wrong?

Thanks a million!

EDIT 1

Here is the implementation for HPSDbBase:

#import "HPSDbBase.h"

@implementation HPSDbBase

@dynamic id;
@dynamic json;


-(id)getJSONElement:(NSString*)key
{
    NSData *jsonData = [[self json] dataUsingEncoding:NSUTF8StringEncoding];

    NSError *e = nil;

    id jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options: NSJSONReadingMutableContainers error: &e];
    NSDictionary *jsonDictionary = (NSDictionary *)jsonObject;

    id rc = [jsonDictionary objectForKey:key];

    return rc;
}

@end 

解决方案

I tracked down the problem.

I had renamed my core-data object. I renamed everything I could see regarding the name of the core-data object, but it was obviously not enough. I deleted the core-data entity, then recreated a brand new one with the right name and everything started working.

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