NSManagedObject自定義類 - NSInvalidArgumentException無法識別的選擇器 -

Question

我有一個自定義NSManagedObject類看起來像這樣。

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

@class Ingredient, MenuCategory, Price, ItemSize; 

@interface Item : NSManagedObject 

@property (nonatomic, retain) NSNumber * collected; 
@property (nonatomic, retain) NSString * desc; 
@property (nonatomic, retain) NSString * instructions; 
@property (nonatomic, retain) NSString * name; 
@property (nonatomic, retain) NSNumber * quantity; 
@property (nonatomic, retain) NSNumber * selected; 
@property (nonatomic, retain) MenuCategory *menuCategory; 
@property (nonatomic, retain) NSSet *prices; 
@property (nonatomic, retain) NSSet *itemSizes; 
@property (nonatomic, retain) NSSet *itemIngredients; 


-(NSMutableSet *)mutablePrices; 
-(NSMutableSet *)mutableItemIngredients; 

@end 

#import "Item.h" 
#import "Ingredient.h" 
#import "MenuCategory.h" 
#import "Price.h" 
#import "ItemSize.h" 


@implementation Item 

@dynamic collected; 
@dynamic desc; 
@dynamic instructions; 
@dynamic name; 
@dynamic quantity; 
@dynamic selected; 
@dynamic itemIngredients; 
@dynamic menuCategory; 
@dynamic prices; 
@dynamic itemSizes; 


-(NSMutableSet *)mutablePrices{ 

    return [self mutableSetValueForKey:@"prices"]; 
} 

-(NSMutableSet *)mutableItemIngredients{ 

    return [self mutableSetValueForKey:@"itemIngredients"]; 
} 

@end 

沒有那麼特別RIGHT ??? 以下應該工作正確？

[item.mutablePrices addObject:newPrice] 

，但它不給我下面的錯誤

2014-03-30 10:25:34.594 restos[1192:60b] -[NSManagedObject mutablePrices]: unrecognized selector sent to instance 0xe8d72c0 
2014-03-30 10:25:34.597 restos[1192:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSManagedObject mutablePrices]: unrecognized selector sent to instance 0xe8d72c0' 

，但是當我這樣做

[[item mutableSetValueForKey:@"prices"] addObject:newPrice]; 

工作得很好---我所知道的是一些簡單的出於某種原因我看不到它----

先謝謝你

Answer 1

錯誤消息

-[NSManagedObject mutablePrices]: unrecognized selector sent to instance 0xe8d72c0 

表明您item對象不是Item類的一個實例。可能的原因可能是您沒有將實體的類別設置爲核心數據 模型檢查器中的「項目」。

通常情況下，如果您讓Xcode生成NSManagedObject子類文件（從編輯菜單中）並將您的自定義方法添加到類別類別中，那麼它通常不太容易出錯。或者，使用"mogenerator"。