在 iphone 中插入的 CoreData 序列与我插入的不同

Question

我在coredata中插入了一些对象，但是当我检索它们时，它们的顺序与我插入的不同，甚至索引也得到了妥善管理，

-(void)addQuestion
 {
NSManagedObjectContext *context = [self managedObjectContext];

NSMutableArray *array = [[NSMutableArray alloc] init];

[array addObject:@"What is capital of Australia?"];
[array addObject:@"What is capital of Canada?"];
[array addObject:@"What is capital of UAE?"];
[array addObject:@"What is capital of USA?"];
[array addObject:@"What is capital of Pakistan?"];
[array addObject:@"What is capital of China?"];
[array addObject:@"What is capital of UK?"];
[array addObject:@"What is capital of Russia?"];
[array addObject:@"What is capital of Romania?"];
[array addObject:@"What is capital of Germany?"];


for (int x = 0; x<10; x++) {

    Question *question = [NSEntityDescription
                          insertNewObjectForEntityForName:@"Question"
                          inManagedObjectContext:context];
    question.question =  [array objectAtIndex:x];
    question.answer = @"Testville";
    question.mcqsa = @"Sydney";
    question.mcqsb = @"Canbera";
    question.mcqsc =  @"Berlin";
    question.mcqsd = @"Bern";

}



NSError *error;
if (![context save:&error]) {
    NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}

// Test listing all FailedBankInfos from the store
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Question"
                                          inManagedObjectContext:context];
[fetchRequest setEntity:entity];


NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];

for (Question *info in fetchedObjects) {
    NSLog(@"Name: %@", info.question);
}

}

日志显示

2013-06-04 17:59:59.978 iQuiz[972:c07] Name: What is capital of Romania?
2013-06-04 17:59:59.979 iQuiz[972:c07] Name: What is capital of Australia?
2013-06-04 17:59:59.979 iQuiz[972:c07] Name: What is capital of Pakistan?  
2013-06-04 17:59:59.980 iQuiz[972:c07] Name: What is capital of Russia? 
2013-06-04 17:59:59.980 iQuiz[972:c07] Name: What is capital of USA?
2013-06-04 17:59:59.981 iQuiz[972:c07] Name: What is capital of UK?
2013-06-04 17:59:59.981 iQuiz[972:c07] Name: What is capital of UAE?
2013-06-04 17:59:59.982 iQuiz[972:c07] Name: What is capital of Germany?
2013-06-04 17:59:59.982 iQuiz[972:c07] Name: What is capital of China?
2013-06-04 17:59:59.982 iQuiz[972:c07] Name: What is capital of Canada?

Answer 1

这是正常行为。不保证广告订单（或与此相关的任何订单）。如果顺序很重要，请添加一个额外的属性 index，您可以在获取对象时递增并对其进行排序。

Answer 2

解决这个问题的另一种方法是建立关系而不是属性。然后将关系设置为有序。

Answer 3

是的，这很正常。完全。只需自己跟踪 id 并在查询时使用 NSSortDescriptor 对其进行排序。这是推荐的方法。