當我將新的託管對象添加到關係集時，爲什麼我的應用崩潰了？

Question

我有這個簡單的核心數據模型：

問題，答案

每一個每一個問題都有4個答案。

的代碼如下： Question.m

@interface Question : NSManagedObject 
{ 
} 

@property (nonatomic, retain) NSString * questionText; 
@property (nonatomic, retain) NSSet* answers; 
@property (nonatomic, retain) Package * package; 

@end 


@interface Question (CoreDataGeneratedAccessors) 
- (void)addAnswersObject:(NSManagedObject *)value; 
- (void)removeAnswersObject:(NSManagedObject *)value; 
- (void)addAnswers:(NSSet *)value; 
- (void)removeAnswers:(NSSet *)value; 

@end 

Answer.m

@class Question; 

@interface Answer : NSManagedObject 
{ 
} 

@property (nonatomic, retain) NSString * answerText; 
@property (nonatomic, retain) NSNumber * correct; 
@property (nonatomic, retain) Question * question; 

@end 

問題是，當我嘗試回答添加到與addAnswersObject的問題。

這是崩潰的應用程序的代碼的一部分：

for (CXMLElement *theElement in theNodes) 
    { 
     Question *qst = [NSEntityDescription insertNewObjectForEntityForName:@"Question" inManagedObjectContext:moc]; 

     // Create a counter variable as type "int" 
     int counter; 

     // Loop through the children of the current node 
     for(counter = 0; counter < [theElement childCount]; counter++) { 



      if([[[theElement childAtIndex:counter] name] isEqualToString: @"question"]) 
       [qst setQuestionText:[[theElement childAtIndex:counter] stringValue]]; 
      if([[[theElement childAtIndex:counter] name] isEqualToString: @"answer"]) { 
       Answer *answer = [NSEntityDescription insertNewObjectForEntityForName:@"Answer" inManagedObjectContext:moc]; 

       [answer setAnswerText:[[theElement childAtIndex:counter] stringValue]]; 

       CXMLElement *answerElement = (CXMLElement *)[theElement childAtIndex:counter]; 

       if([[[answerElement attributeForName:@"correct"] stringValue] isEqualToString:@"YES"]) { 
        [answer setCorrect:[NSNumber numberWithBool:YES]]; 
       } else { 
        [answer setCorrect:[NSNumber numberWithBool:NO]]; 
       } 

       [qst addAnswersObject:answer]; //The app crash here 

      } 

     } 

這是日誌從控制檯：

2010-05-24 20：02：38.475 Fgq [5670： 40b] *** - [NSUserDefaults objectForKey：]：發送到釋放實例的消息 0x3c179a0程序接收信號： 「EXC_BAD_ACCESS」。

我從對象數據模型中多次重新導出所有對象而沒有成功，我檢查了所有關係，看起來一切正常。

會出現什麼樣的問題？

Answer 1

如果在qst實例的-insertNewObjectForEntityName:inManagedObjectContext:調用之後立即添加NSLog(@"qst: %@:, qst);，控制檯會報告什麼？

如果在answer實例的-insertNewObjectForEntityName:inManagedObjectContext:調用之後立即添加NSLog(@"answer: %@:, answer);，控制檯會報告什麼？

Answer 2

這裏是NSLog報告（@「qst：％@」，qst）;

2010-05-24 23：37：33.948 FGQ [452：207] QST： （實體： 問題; ID：0x3c19ab0 ;數據：{ 答案=（ ）; 包=無; questionText =零;}）