NSFetchedResultsController不会在reloadData上更改

我有一个Master-Detail窗体中的iOS应用程序，其中由用户创建的帖子显示在详细信息中显示的主视图和注释中。当我选择一篇文章时，我可以看到所有评论，但是当我回去选择另一篇文章时，数据不会更改为下一篇文章的评论。NSFetchedResultsController不会在reloadData上更改

我称这种现象viewDidLoad

self.fetchedResultsController = nil; 
[self.tableView reloadData];

但没有任何反应。

这里是我的fetchedResultsController

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

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

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"question == %@", self.detailItem]; 
    [fetchRequest setPredicate:predicate]; 

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

    // Edit the sort key as appropriate. 
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creator" ascending:YES]; 
    NSArray *sortDescriptors = @[sortDescriptor]; 

    [fetchRequest setSortDescriptors:sortDescriptors]; 

    // 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:@"Master"]; 
    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 in detail %@, %@", error, [error userInfo]); 
     abort(); 
    } 

    return _fetchedResultsController; 
}

来源

2013-03-19 Slayter

您的提取结果控制器不刷新的原因是您设置了缓存。你要么需要通过nil作为缓存名称，或删除之前的高速缓存刷新FRC：

[NSFetchedResultsController deleteCacheWithName:@"Master"]

来源

2013-03-19 13:33:41

这做到了！设置缓存为零为我工作。核心数据对我来说是新的和可怕的，但我正在慢慢获得它。谢谢！ – Slayter 2013-03-19 13:53:31

代码只是试试这个代码：

调用此方法之前不要忘了写self.fetchedResultsController = nil;

- (NSFetchedResultsController *)fetchedResultsController // attaches an NSFetchRequest to this UITableViewController 
{ 
    if (_fetchedResultsController != nil) 
    { 
     return _fetchedResultsController; 
    } 

    NSLog(@"Length:: %d",[[_fetchedResultsController mutableCopy] length]); 

    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Comment"]; 
    [fetchRequest setIncludesSubentities:YES]; 

    // Sort by Application name 
    NSSortDescriptor* sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"creator" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)]; 
    //Sort by CommandNameloca 
    NSArray* sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor1, nil]; 
    [fetchRequest setSortDescriptors:sortDescriptors]; 

    [fetchRequest setFetchBatchSize:100]; 

    ordersArr=[[NSMutableArray alloc]initWithArray:sortDescriptors]; 

    NSLog(@"----- ordersArr Count == %d",[ordersArr count]); 

    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:@"creator" cacheName:@"Master"]; 
    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; 
}

来源

2013-03-19 06:05:06

你有没有打过电话的复位代码viewDidAppear而不是？通常在视图的生命周期中不会多次调用viewDidLoad。当视图实际上出现在屏幕上时调用viewWillAppear/viewDidAppear。

您是否试图断开您的表重载方法以确保它实际上被调用？

来源

2013-03-19 13:07:28

NSFetchedResultsController不会在reloadData上更改

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