核心数据委托方法不止一次调用

Question

我正在使用XMPP创建一个FBChat.I为coredata和fetchedResults创建了单独的类。

CoreDataClass：

@implementation CoreDataClass 

@synthesize managedObjectContext = __managedObjectContext; 
@synthesize managedObjectModel = __managedObjectModel; 
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator; 


- (NSManagedObjectContext *)managedObjectContext 
{ 

    if (__managedObjectContext != nil) 
    { 
     return __managedObjectContext; 
    } 

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator]; 
    if (coordinator != nil) 
    { 
     __managedObjectContext = [[NSManagedObjectContext alloc] init] ; 
     [__managedObjectContext setPersistentStoreCoordinator:coordinator]; 
    } 
    return __managedObjectContext; 
} 


- (NSManagedObjectModel *)managedObjectModel 
{ 
    if (__managedObjectModel != nil) 
    { 
     return __managedObjectModel; 
    } 
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Chat" withExtension:@"momd"]; 
    __managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL]; 
    return __managedObjectModel; 
} 


- (NSPersistentStoreCoordinator *)persistentStoreCoordinator 
{ 
    if (__persistentStoreCoordinator != nil) 
    { 
     return __persistentStoreCoordinator; 
    } 
    AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate]; 
    NSURL *storeURL = [[delegate applicationDocumentsDirectory] URLByAppendingPathComponent:@"FacebookChat.sqlite"]; 
    NSError *error = nil; 
    __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 



    if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) 
    { 

     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     abort(); 
    }  

    return __persistentStoreCoordinator; 
} 
- (void)saveContext 
{ 
    NSError *error = nil; 
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext; 
    if (managedObjectContext != nil) 
    { 
     if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) 
     { 
         NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      abort(); 
     } 
    } 
} 

FetchedControlClass：在MainChatClass两类

@implementation FetchedControllClass 
@synthesize fetchedResultsController; 

#pragma mark Fetched Results 

- (NSFetchedResultsController *)fetchedResultsController 
{ 
    CoreDataClass *coreDataObject=[[CoreDataClass alloc]init]; 

    if (fetchedResultsController != nil) { 
     return fetchedResultsController; 
    } 


    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Conversation" inManagedObjectContext:coreDataObject.managedObjectContext]; 
    [fetchRequest setEntity:entity]; 
    [fetchRequest setFetchBatchSize:20]; 
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"facebookName" ascending:YES]; 

    NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];  
    [fetchRequest setSortDescriptors:sortDescriptors]; 
    [sortDescriptor release]; 

    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:coreDataObject.managedObjectContext sectionNameKeyPath:nil cacheName:@"Master"] ; 
    [fetchRequest release]; 
    aFetchedResultsController.delegate = self; 
    self.fetchedResultsController = aFetchedResultsController; 
    [aFetchedResultsController release]; 
    NSError *error = nil; 
    if (![self.fetchedResultsController performFetch:&error]) { 

     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     abort(); 
    } 
    [coreDataObject release]; 
    return fetchedResultsController; 
}  

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller 
{ 
    AlertListVC *alertListObject=[[AlertListVC alloc]initWithNibName:@"AlertListVC" bundle:nil]; 

    [alertListObject.tableView beginUpdates]; 
    [alertListObject release]; 
} 

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo 
      atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type 
{ 
    AlertListVC *alertListObject=[[AlertListVC alloc]initWithNibName:@"AlertListVC" bundle:nil]; 


    switch(type) { 
     case NSFetchedResultsChangeInsert: 
      [alertListObject.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeDelete: 
      [alertListObject.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 
    } 
    [alertListObject release]; 
} 

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject 
     atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type 
     newIndexPath:(NSIndexPath *)newIndexPath 
{ 
    AlertListVC *alertListObject=[[AlertListVC alloc]initWithNibName:@"AlertListVC" bundle:nil]; 

    UITableView *tableView = alertListObject.tableView; 

    switch(type) { 
     case NSFetchedResultsChangeInsert: 
      [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeDelete: 
      [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeUpdate: 
      [alertListObject configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; 
      break; 

     case NSFetchedResultsChangeMove: 
      [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade]; 
      break; 
    } 
    [alertListObject release]; 
} 

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller 
{ 
    AlertListVC *alertListObject=[[AlertListVC alloc]initWithNibName:@"AlertListVC" bundle:nil]; 
    [alertListObject.tableView endUpdates]; 
    [alertListObject release]; 

} 

我做了对象，并添加来自coredata的谈话ConversationClass

Conversation *conversation = (Conversation *)[NSEntityDescription 
                  insertNewObjectForEntityForName:@"Conversation" 
                  inManagedObjectContext:coreDataClassObject.managedObjectContext]; 

我能获取fetchedResults但 问题是： Coredata方法得到了两次调整（所以文件创建两次）。如果我选​​择朋友聊天，那么应用程序将崩溃。我用僵尸来追踪问题。它显示了一些错误， 负责来电者： 1 MainChatClass的tableView：didSelectRowAtIndexPath方法] 2 NSFetchedResultsController（私有方法）_managedObjectContextDidChange]

我试过很多次，但仍然得到这些方法的错误。 如果有人有这个想法，那么请帮助我。 在此先感谢

Answer 1

在每个FRC代表方法中，您都会创建一个新的alertListObject。这是没有意义的。您必须将更新消息发送到您现有的表格视图。

发生崩溃是因为alertListObject.tableView是nil对于新创建的视图控制器。