爲什麼這個獲取請求不返回

我想過濾一些管理對象。結果雖然是zip。爲什麼這個獲取請求不返回

過濾器是「名稱」。名稱是根視圖提供給此詳細視圖的元素。名稱記錄確定：

[48582:2754928] name: To Be 
[48582:2754928] predicate: name == @"name" 

name = [self.detailItem valueForKey:@"name"]; 

NSError *error; 
    if (![[self fetchedResultsController] performFetch:&error]) { 
     // Update to handle the error appropriately. 
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     exit(-1); // Fail 
    }

和FetchResultsController如下：

NSError *error = nil; 
    name = [self.detailItem valueForKey:@"name"]; 
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"VerbEntity" inManagedObjectContext:self.managedObjectContext]; 
    [fetchRequest setEntity:entity]; 
    predicate = [NSPredicate predicateWithFormat:@"name == %@",@"name"]; 
    NSLog(@"name: %@", name); 
    fetchRequest.predicate = predicate; 
    NSLog(@"predicate: %@", predicate); 

// Create the sort descriptors array. 
    NSArray *sortDescriptorArray = nil; 

    // Declare sort descriptors 
    NSSortDescriptor *sortDescriptorPrimary = nil; 




    sortDescriptorPrimary = [[NSSortDescriptor alloc] initWithKey:@"position" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)]; 

    // Set sort descriptor array 
    sortDescriptorArray = @[sortDescriptorPrimary]; 

    // Apply sort descriptors to fetch request 
    [fetchRequest setSortDescriptors:sortDescriptorArray]; 

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

    NSLog(@"fetchedObjects count: %lu", (unsigned long)fetchedObjects.count); 
    _fetchedResultsController.delegate = self; 
    return _fetchedResultsController; 
}

做任何事情脫穎而出靠不住？謝謝你的幫助。

來源

2014-09-24 David DelMonte

沒有謂詞，你的獲取返回的東西嗎？如果name是一個'NSString'，那麼使用'@「名稱LIKE％@」'怎麼辦？你不是想把'@「name ==％@」，@「name」'改成'@「name ==％@」，name'，這可能是一個錯誤，並解釋了爲什麼你沒有找到任何東西在你的提取？ – Larme 2014-09-24 14:37:41

如果初始化提取請求的方式不同，會發生什麼情況？也許試試 [NSFetchRequest fetchRequestWithEntityName：@「VerbEntity」]; 另外，什麼是_fetchedResultsController？一個NSFetchedResultsController？如果是這樣，你需要在其上設置NSFetchRequest對象。 – 2014-09-24 15:33:20

謝謝大家。你的答案組合解決了這個問題。 – 2014-09-24 18:32:19

它看起來像你的_fetchedResultsController沒有對其設置獲取請求。也許有超過這個代碼片斷顯示...但這可能會工作

NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"VerbEntity"]; 
request.predicate = [NSPredicate predicateWithFormat:@"name == %@",@"name"]; 

// Note: Sort descriptors available depend on the backing store type. 
NSSortDescriptor *sortDescriptorPrimary = [[NSSortDescriptor alloc] initWithKey:@"position"   
                     ascending:YES 
                     selector:@selector(localizedCaseInsensitiveCompare:)]; 

request.sortDescriptors = @[sortDescriptorPrimary]; 

// The request needs to be set on the controller. 
NSFetchedResultsController *controller = 
    [[NSFetchedResultsController alloc] initWithFetchRequest:request 
             managedObjectContext:self.managedObjectContext 
              sectionNameKeyPath:nil 
                cacheName:nil]; 
// The controller needs to perform the fetch. 
[controller performFetch:nil]; // Optionally pass in an NSError. 
controller.delegate = self; 
_fetchedResultsController = controller; 
return controller;

來源

2014-09-24 15:44:11

爲什麼這個獲取請求不返回

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