NSDictionary NSManagedObject

Question

如何将字典数据转换为NSManagedObject数据？我使用了propertiesToFetch，它返回字典数据。但我想要NSManagedObject数据。请引导我

[fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects:catalogID, pageID, nil]];
[fetch setResultType:NSDictionaryResultType];
[fetch setReturnsDistinctResults : YES];
NSError* error = nil;
self.resultPageArray = [context executeFetchRequest:fetch error:&error];

当我将类型更改为NSManagedObjectResultType时，就得到了不明确的数据。我读到，在使用propertiesToFetch时，它以字典格式保存数据。但是我想要获得不同的数据，并将其保存到NSManagedObjects中。

Answer 1

我已经解决了这个问题。我正在获取NSManagedObjects的数据。之后，我将数据保存到另一个数组，不重复。并返回新的数组。

self.resultPageArray = [context executeFetchRequest:fetch error:&error];            
NSMutableArray *resultantFinalArr = [[NSMutableArray alloc] init];
for (int i = 0; i<resultPageArray.count; i++)
{
    catalogPageDataModel *atIndexI = [resultPageArray objectAtIndex:i];
    BOOL find = NO;
    for (catalogPageDataModel* catalogPageDataModel in resultantFinalArr)
    {
        if (catalogPageDataModel.pageid.intValue == atIndexI.pageid.intValue)
        {
            find = YES;
            break;
        }
    }
    if (!find)
        [resultantFinalArr addObject:atIndexI];
}
            NSLog(@"result array count %lu",(unsigned long)resultantFinalArr.count);
NSLog (@"names: %@",resultantFinalArr);
return resultantFinalArr;

Answer 2

尝尝这个,

[fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects:catalogID, pageID, nil]];
[fetch setResultType:NSManagedObjectResultType];
[fetch setReturnsDistinctResults : YES];
NSError* error = nil;
self.resultPageArray = [context executeFetchRequest:fetch error:&error];

我的代码：

NSError *error = nil;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"BookInfo"
                                          inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setPropertiesToFetch:@[catalogID, pageID]];

[fetchRequest setPredicate: [NSPredicate predicateWithFormat:@"(bookId == %@)",strId]];

NSArray *fetchedItems = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];

if( fetchedItems.count > 0 ) {
    BookInfo *bInfo =  [fetchedItems lastObject];
    NSLog(@"%@",bInfo.bookName);
}