使用UICollectionView和NSFetchedResultsController不保存 [英] Use UICollectionView and NSFetchedResultsController doesn't save

问题描述

我在github上使用一个项目，让我使用 NSFetchedResultsController 和 UICollectionView a href =https://github.com/AshFurrow/UICollectionView-NSFetchedResultsController =nofollow>此

在我的项目中，我有一个具有两个实体元素和文档的核心数据，在元素和文档，因此元素可以有更多 ，但是文档只能有一个 Element code> AppDelegate ：

   - （BOOL）application：（UIApplication *）application didFinishLaunchingWithOptions ：（NSDictionary *）launchOptions 
 {
 self.window = [[UIWindow alloc] initWithFrame：[[UIScreen mainScreen] bounds]]; 
 //在应用程序启动后覆盖自定义点。 
 
 ElementViewController * elementView = [[ElementViewController alloc] initWithNibName：@ElementViewControllerbundle：nil]; 
 elementView.managedObjectContext = self.managedObjectContext; 
 
 DocumentViewController * documentView = [[DocumentViewController alloc] initWithNibName：@DocumentViewControllerbundle：nil]; 
 documentView.managedObjectContext = self.managedObjectContext; 
 
 elementView.documentView = documentView; 
 
 UINavigationController * navController = [[UINavigationController alloc] initWithRootViewController：elementView]; 
 
 self.window.rootViewController = navController; 
 [self.window makeKeyAndVisible]; 
 return YES; 
} 
  

这是App委托，然后在 ElementViewController 我有一个 UICollectionView 与 NSFetchedResultsController ，并且所有工作确定，当我选择 UICollectionViewCell 我打开 DocumentViewController ：

   - （void）collectionView：（UICollectionView *）collectionView didSelectItemAtIndexPath：（NSIndexPath *）indexPath 
 {
 
 self.documentView.element = [self.fetchedResultsController objectAtIndexPath：indexPath]; 
 [self.navigationController pushViewController：self.documentView animated：YES]; 
 
} 
  

那么这是我的 DocumentViewController。 h ：

  #import< UIKit / UIKit.h> 
 #importElement.h
 
 @interface DocumentViewController：UIViewController< NSFetchedResultsControllerDelegate> 
 
 @property（strong，nonatomic）NSManagedObjectContext * managedObjectContext; 
 @property（weak，nonatomic）IBOutlet UICollectionView * collectionView; 
 @property（strong，nonatomic）NSFetchedResultsController * fetchedResultsController; 
 
 @property（strong，nonatomic）Element * element; 
 
 @end 
  

还有这里的 NSFetchedResultsController ，元素标题的谓语中的过滤器：

   - （NSFetchedResultsController *）fetchedResultsController 
 {
 if（_fetchedResultsController！= nil）{
 return _fetchedResultsController; 
} 
 
 NSFetchRequest * fetchRequest = [[NSFetchRequest alloc] init]; 
 //根据需要编辑实体名称。 
 NSEntityDescription * entity = [NSEntityDescription entityForName：@DocumentinManagedObjectContext：self.managedObjectContext]; 
 [fetchRequest setEntity：entity]; 
 
 //将批量大小设置为合适的数量。 
 [fetchRequest setFetchBatchSize：20]; 
 
 //根据需要编辑排序键。 
 NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey：@docDateascending：NO]; 
 NSArray * sortDescriptors = @ [sortDescriptor]; 
 
 [fetchRequest setSortDescriptors：sortDescriptors]; 
 
 [fetchRequest setPredicate：[NSPredicate predicateWithFormat：@SUBQUERY（element，$ b，$ b.name ==％@）。@ count> 0，self.element.name]]; 
 
 //如果适当，编辑段名称键路径和缓存名称。 
 //节的名称键路径的nil表示没有节。 
 NSFetchedResultsController * aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest：fetchRequest managedObjectContext：self.managedObjectContext sectionNameKeyPath：nil cacheName：nil]; 
 aFetchedResultsController.delegate = self; 
 self.fetchedResultsController = aFetchedResultsController; 
 
 NSError * error = nil; 
 if（！[self.fetchedResultsController performFetch：& error]）{
 //用代码替换这个实现，以适当地处理错误。 
 // abort（）导致应用程序生成崩溃日志并终止。您不应在运送应用程序中使用此功能，但在开发过程中可能很有用。 
 NSLog（@未解析的错误％@，％@，错误，[错误userInfo]）; 
 abort（）; 
} 
 
 return _fetchedResultsController; 
} 
  

然后我也添加了这样：

   - （void）viewWillAppear：（BOOL）animated 
 {
 [super viewWillAppear：animated]; 
 
 [self ReloadCollectionView]; 
 
 [self addDocument]; 
} 
 
  - （void）reloadTableView 
 {
 self.fetchedResultsController = nil; //因为不是每次都搜索不同的元素
 NSError * error; 
 if（！[[self fetchedResultsController] performFetch：& error]）{
 NSLog（@Error in search％@，％@，error，[error userInfo]）; 
} else {
 [self.collectionView reloadData]; 
} 
} 
  

然后在viewWillAppear中有 addDocument 方法：

   - （void）addDocument 
 {
 Document * document =（Document *）[NSEntityDescription 
 insertNewObjectForEntityForName：@Document
 inManagedObjectContext：self.managedObjectContext]; 
 
 [document setDocName：[title contents]]; 
 [document setElement：self.element]; //这里应用程序崩溃
} 
  

我收到这些错误：

  CoreData：错误：严重的应用程序错误。在核心数据更改处理期间捕获异常。这通常是NSManagedObjectContextObjectsDidChangeNotification的观察器中的错误。无法对非集合对象执行集合求值。使用userInfo（null）
 2013-01-25 10：28：56.392 App [383：c07] ***由于未捕获异常NSInternalInconsistencyException终止应用程序，原因：集合对象。
  

任何人都可以帮助我？

EDIT：
这是NSManagedObjectClass：

  #import< Foundation / Foundation.h> 
 #import< CoreData / CoreData.h> 
 
 @class文档; 
 
 @interface元素：NSManagedObject 
 
 @property（nonatomic，retain）NSString * dateFormat; 
 @property（nonatomic，retain）NSString * dateFormat2; 
 @property（nonatomic，retain）id img; 
 @property（nonatomic，retain）NSDate * imgDate; 
 @property（nonatomic，retain）NSString * imgUrl; 
 @property（nonatomic，retain）NSString * language; 
 @property（nonatomic，retain）NSString * name; 
 @property（nonatomic，retain）NSString * name2; 
 @property（nonatomic，retain）NSString * pathDocuments; 
 @property（nonatomic，retain）NSNumber * releaseDateWeek; 
 @property（nonatomic，retain）NSNumber * type; 
 @property（nonatomic，retain）NSSet * documents; 
 @end 
 
 @interface元素（CoreDataGeneratedAccessors）
 
  - （void）addDocumentsObject：（Document *）value; 
  - （void）removeDocumentsObject：（Document *）value; 
  - （void）addDocuments：（NSSet *）values; 
  - （void）removeDocuments：（NSSet *）values; 
 
 @end 
 
 @interface ImageToDataTransformer：NSValueTransformer {
} 
 @end 
 
 Document.h 
 
 #import< Foundation / Foundation.h> 
 #import< CoreData / CoreData.h> 
 
 @class元素; 
 
 @interface文档：NSManagedObject 
 
 @property（nonatomic，retain）NSDate * docDate; 
 @property（nonatomic，retain）id docImage; 
 @property（nonatomic，retain）NSString * docName; 
 @property（nonatomic，retain）NSString * docPath; 
 @property（nonatomic，retain）NSNumber * docSize; 
 @property（nonatomic，retain）NSString * docUrl; 
 @property（nonatomic，retain）NSNumber * isDownloading; 
 @property（nonatomic，retain）NSNumber * isStored; 
 @property（nonatomic，retain）NSNumber * pageNumber; 
 @property（nonatomic，retain）NSString * password; 
 @property（nonatomic，retain）NSNumber * progressBar; 
 @property（nonatomic，retain）Element * element; 
 
 @end 
  

解决方案

问题看起来是这样的：

  [fetchRequest setPredicate：[NSPredicate predicateWithFormat：@SUBQUERY（element，$ b，$ b.name ==％@）。@ count> 0，self.element.name]]; 
 

'element'不能解析为一个集合（按照SUBQUERY的要求），而只是一个对象。

请参阅： http://developer.apple.com/library/Mac/#documentation/Cocoa/Reference/Foundation/Classes/NSExpression_Class/Reference/NSExpression.html

I'm using a project find on github that lets me use NSFetchedResultsController and UICollectionView, the project is this

in my project i have a Core Data with two Entity, Element and Document, there is a relationship one to many between Element and Document, so an Element can have more Document, but a Document can have only one Element, then i do this in the AppDelegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.

ElementViewController *elementView = [[ElementViewController alloc] initWithNibName:@"ElementViewController" bundle:nil];
elementView.managedObjectContext = self.managedObjectContext;

DocumentViewController *documentView = [[DocumentViewController alloc] initWithNibName:@"DocumentViewController" bundle:nil];
documentView.managedObjectContext = self.managedObjectContext;

elementView.documentView = documentView;

UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:elementView];

self.window.rootViewController = navController;
[self.window makeKeyAndVisible];
return YES;
 }

this is the App delegate, then in ElementViewController i have a UICollectionView with NSFetchedResultsController, and all works ok, when i select a UICollectionViewCell i open the DocumentViewController:

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{

self.documentView.element = [self.fetchedResultsController objectAtIndexPath:indexPath];
[self.navigationController pushViewController:self.documentView animated:YES];

}

then this is my DocumentViewController.h:

#import <UIKit/UIKit.h>
#import "Element.h"

@interface DocumentViewController : UIViewController <NSFetchedResultsControllerDelegate>

@property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (weak, nonatomic) IBOutlet UICollectionView *collectionView;
@property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController;

@property (strong, nonatomic) Element *element;

@end

And also here i have the NSFetchedResultsController, the filter in the predicate for the Element title:

- (NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController != nil) {
    return _fetchedResultsController;
}

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Document" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];

// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];

// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"docDate" ascending:NO];
NSArray *sortDescriptors = @[sortDescriptor];

[fetchRequest setSortDescriptors:sortDescriptors];

[fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"SUBQUERY(element, $b, $b.name == %@).@count > 0", self.element.name]];

// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;

NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
    // Replace this implementation with code to handle the error appropriately.
    // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}

return _fetchedResultsController;
}

and then i have add also this:

- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];

[self reloadCollectionView];

[self addDocument];
}

- (void)reloadTableView
{
self.fetchedResultsController = nil; //Because not search every time for different Element
NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) {
    NSLog(@"Error in search %@, %@", error, [error userInfo]);
} else {
    [self.collectionView reloadData];
}
}

then in the viewWillAppear there is the addDocument method:

- (void)addDocument
{
Document *document = (Document *)[NSEntityDescription
                                          insertNewObjectForEntityForName:@"Document"
                                          inManagedObjectContext:self.managedObjectContext];

[document setDocName:[title contents]];
[document setElement:self.element]; //here the app crash
}

and i receive these error:

    CoreData: error: Serious application error.  Exception was caught during Core Data change processing.  This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification.  Can't perform collection evaluate with non-collection object. with userInfo (null)
2013-01-25 10:28:56.392 App[383:c07] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Can't perform collection evaluate with non-collection object.'

anyone can help me?

EDIT: This is the NSManagedObjectClass:

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

@class Document;

@interface Element : NSManagedObject

@property (nonatomic, retain) NSString * dateFormat;
@property (nonatomic, retain) NSString * dateFormat2;
@property (nonatomic, retain) id img;
@property (nonatomic, retain) NSDate * imgDate;
@property (nonatomic, retain) NSString * imgUrl;
@property (nonatomic, retain) NSString * language;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSString * name2;
@property (nonatomic, retain) NSString * pathDocuments;
@property (nonatomic, retain) NSNumber * releaseDateWeek;
@property (nonatomic, retain) NSNumber * type;
@property (nonatomic, retain) NSSet *documents;
@end

@interface Element (CoreDataGeneratedAccessors)

- (void)addDocumentsObject:(Document *)value;
- (void)removeDocumentsObject:(Document *)value;
- (void)addDocuments:(NSSet *)values;
- (void)removeDocuments:(NSSet *)values;

@end

@interface ImageToDataTransformer : NSValueTransformer {
}
@end

Document.h

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

@class Element;

@interface Document : NSManagedObject

@property (nonatomic, retain) NSDate * docDate;
@property (nonatomic, retain) id docImage;
@property (nonatomic, retain) NSString * docName;
@property (nonatomic, retain) NSString * docPath;
@property (nonatomic, retain) NSNumber * docSize;
@property (nonatomic, retain) NSString * docUrl;
@property (nonatomic, retain) NSNumber * isDownloading;
@property (nonatomic, retain) NSNumber * isStored;
@property (nonatomic, retain) NSNumber * pageNumber;
@property (nonatomic, retain) NSString * password;
@property (nonatomic, retain) NSNumber * progressBar;
@property (nonatomic, retain) Element *element;

@end

解决方案

The problem looks to be that that in:

[fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"SUBQUERY(element, $b, $b.name == %@).@count > 0", self.element.name]];

'element' does not resolve to a collection (as required by SUBQUERY), but merely a single object.

See: http://developer.apple.com/library/Mac/#documentation/Cocoa/Reference/Foundation/Classes/NSExpression_Class/Reference/NSExpression.html

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