问题描述
以前有人遇到过这种情况吗？
Has anyone run into this before?
当我选择从我的tableView中删除一行（由FRC填充）时，应用程序不会崩溃或挂起。它不做任何事情。删除按钮保持选中，如果我单击模拟器上的其他位置，删除按钮取消选择和消失，但单元格从来没有从UI中删除。我确定有一个愚蠢的监督我在这里，但我不能发现它。下面是我的代码的相关部分。
When I choose to delete a row from my tableView (populated by an FRC), the app doesn't crash or hang. It doesn't do anything. The delete button stays selected and if I click elsewhere on the simulator, the delete button deselects and disappears, but the cell is never removed form the UI. I'm sure there is a dumb oversight I am making here, but I can't spot it. Below are the relevant portions of my code.
我有我的UITableViewController接口这样声明：
I have my UITableViewController interface declared as such:
#import <UIKit/UIKit.h>
#import "RubricAppDelegate.h"
@interface ClassList : UITableViewController <NSFetchedResultsControllerDelegate> {
NSMutableArray *classList;
NSFetchedResultsController *fetchedResultsController;
NSManagedObjectContext *managedObjectContext;
}
@property(nonatomic,retain) NSMutableArray *classList;
@property(nonatomic, retain) NSFetchedResultsController *fetchedResultsController;
@property(nonatomic, retain) NSManagedObjectContext *managedObjectContext;
- (IBAction) grade:(id)sender;
@end
在其实现文件中，我有：
In its implementation file, I have:
- (void)viewDidLoad {
[super viewDidLoad];
RubricAppDelegate *appDelegate = (RubricAppDelegate *)[[UIApplication sharedApplication] delegate];
managedObjectContext = [appDelegate managedObjectContext];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"myClass" inManagedObjectContext:managedObjectContext];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"classID" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[request setSortDescriptors:sortDescriptors];
[sortDescriptor release];
fetchedResultsController = [[NSFetchedResultsController alloc]
initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil cacheName:nil];
NSError *error;
[fetchedResultsController performFetch:&error];
}
和
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
myClass *result = (myClass *)[fetchedResultsController objectAtIndexPath:indexPath];
[managedObjectContext deleteObject:result];
NSError *error;
[managedObjectContext save:&error];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
//Not yet implemented
}
}
并且
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
UITableView *tableView = self.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:
[self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
$ b
Also
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row == [[fetchedResultsController fetchedObjects] count]) {
return UITableViewCellEditingStyleInsert;
}
return UITableViewCellEditingStyleDelete;
}
上述代码使单元格超出了我获取填充的单元格，但其余的删除单元格。
That above code makes the cell just beyond my fetch-populated cells an insert cell, but the rest delete cells.
我有我的UITableView连接到我的文件的所有者为其委托和数据源在IB。我需要更改以获取 NSFetchedResultsChangeDelete：才能触发？
I have my UITableView connected to my File's Owner for its delegate and datasource in IB. What do I need to change to get NSFetchedResultsChangeDelete: to trigger?
我已将 [managedObjectContext save：& error]; 添加到 commitEditingStyle 通过断点，当我选择删除单元格时，它被点击。我知道保存正在处理正确，因为如果我退出并重新运行应用程序，我选择删除的单元格事实上被删除。
I have added [managedObjectContext save:&error]; to commitEditingStyle and verified via breakpoint that it is being hit when I choose to delete a cell. I know the save is processing correctly, because if I quit and re-run the app, the cells that I chose to delete are in fact deleted.
但是，当我按下删除按钮，仍然没有发生。
However, when I press the delete button, there is still nothing happening. The button stays selected until I click elsewhere, thereby deselecting it.
推荐答案
您可以显示构建<$ c $的代码c> NSFetchedResultsController ？现在你有你的代码保存为@DVG建议，那么你应该得到回调。
Can you show the code that builds the NSFetchedResultsController? Now that you have the save in your code as @DVG suggested then you should be getting callbacks. Perhaps your delegate is not being set properly.
因为我怀疑你没有设置委托 NSFetchedResultsController ：
As I suspected you are not setting the delegate on the NSFetchedResultsController:
[fetchedResultsController setDelegate:self];
您应该在调用 -performFetch ：。
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