Question

我在App Store中有第一个应用程序，我收到的错误是我无法在任何设备上重现的。一位用户报告说，如果没有应用程序崩溃，他就无法删除产品。我已经尝试了所有我能想到的东西来重现并没有运气。 iTunes Connect中没有崩溃报告，所以我报名参加了Crittercism。现在我知道有三个用户遇到了这个问题。

问题是即使使用崩溃日志，我仍然无法弄清楚应用程序崩溃的原因。当我删除项目时，它永远不会崩溃 - 即使是新创建的项目也没有用户输入信息。任何有关可能帮助我缩小问题范围的建议都将受到高度赞赏。该应用程序使用核心数据，产品实体与其他实体的所有删除规则都设置为无效或级联。

崩溃日志表明崩溃的原因是“NSInvalidArgumentException - deleteObject：需要一个非零参数”。这是回溯：

Reported    Name    Reason  App Version     Symbolicated
15-May-12 07:22:06 PM   NSInvalidArgumentException  
-deleteObject: requires a non-nil argument

0   CoreFoundation 0x317a888f __exceptionPreprocess + 162
1   libobjc.A.dylib 0x315f3259 objc_exception_throw + 32
2   CoreData 0x3325cf23 -[NSManagedObjectContext deleteObject:] + 386
3   OnShelf 0x000972e7 0x76000 + 135911
4   CoreFoundation 0x317023fd -[NSObject performSelector:withObject:withObject:] + 52
5   UIKit 0x319f0e07 -[UIApplication sendAction:to:from:forEvent:] + 62
6   UIKit 0x31ab65e7 -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 118
7   CoreFoundation 0x317023fd -[NSObject performSelector:withObject:withObject:] + 52
8   UIKit 0x319f0e07 -[UIApplication sendAction:to:from:forEvent:] + 62
9   UIKit 0x319f0dc3 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 30
10  UIKit 0x319f0da1 -[UIControl sendAction:to:forEvent:] + 44
11  UIKit 0x319f0b11 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 492
12  UIKit 0x319f1449 -[UIControl touchesEnded:withEvent:] + 476
13  UIKit 0x319ef92b -[UIWindow _sendTouchesForEvent:] + 318
14  UIKit 0x319ef319 -[UIWindow sendEvent:] + 380
15  UIKit 0x319d5695 -[UIApplication sendEvent:] + 356
16  UIKit 0x319d4f3b _UIApplicationHandleEvent + 5826
17  GraphicsServices 0x32bd822b PurpleEventCallback + 882
18  CoreFoundation 0x3177c523 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 38
19  CoreFoundation 0x3177c4c5 __CFRunLoopDoSource1 + 140
20  CoreFoundation 0x3177b313 __CFRunLoopRun + 1370
21  CoreFoundation 0x316fe4a5 CFRunLoopRunSpecific + 300
22  CoreFoundation 0x316fe36d CFRunLoopRunInMode + 104
23  GraphicsServices 0x32bd7439 GSEventRunModal + 136
24  UIKit 0x31a03cd5 UIApplicationMain + 1080
25  OnShelf 0x00077207 0x76000 + 4615
26  OnShelf 0x000771bc 0x76000 + 4540

在UITableView中删除产品的代码唯一不寻常的是它首先检查库存中的数字是否为零。如果不是，则显示警告以询问用户他是否确实要删除产品。与我联系的一位用户确实告诉我他是否发生了碰撞，无论库存中的数量是否为零，因此崩溃似乎与显示的警报无关。这是代码：

- (void)tableView:(UITableView *)tableView 
            commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
             forRowAtIndexPath:(NSIndexPath *)indexPath
{
Product *product = [fetchedResultsController objectAtIndexPath:indexPath];

// Alert the user if the item is currently in stock
if ([product.details.quantity intValue] > 0) {
    [self showAlert];

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        lastIndexPath = indexPath;
        toDelete = YES;
        NSLog(@"Yes delete");
    } else {
        toDelete = NO;
    }
} else {
    // Delete the managed object.
    NSManagedObjectContext *myContext = [fetchedResultsController managedObjectContext];
    [myContext deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]];

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


#pragma mark - AlertView Delegate Methods

- (void)showAlert {
    // open a alert with an OK and cancel button
    UIAlertView *alert =[[UIAlertView alloc] initWithTitle: @"Product In Stock"
                                                   message: @"All product data will be deleted" 
                                                  delegate: nil 
                                         cancelButtonTitle: @"Cancel" 
                                         otherButtonTitles:@"OK", nil];
    [alert setDelegate: self];
    [alert show];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    if (buttonIndex == 0) {
        //do nothing
    }
    else
    {
        if( toDelete == YES)
        {
            // Delete the managed object.
            NSManagedObjectContext *myContext = [fetchedResultsController managedObjectContext];
            [myContext deleteObject:[fetchedResultsController objectAtIndexPath: lastIndexPath]];

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

我正在使用Apple教程中的样板NSFetchedResultsController委托方法：

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
// The fetch controller is about to start sending change notifications, so prepare the table view for updates.
[self.tableView beginUpdates];
}


- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject 
                                                            atIndexPath:(NSIndexPath *)indexPath 
                                                            forChangeType:(NSFetchedResultsChangeType)type 
                                                        newIndexPath:(NSIndexPath *)newIndexPath     {

    UITableView *aTableView = self.tableView;

    switch(type) {

        case NSFetchedResultsChangeInsert:
            [aTableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

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

        case NSFetchedResultsChangeUpdate:
            [self configureCell:(DatabaseCell *)[aTableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
            break;

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


- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
                                                            atIndex:(NSUInteger)sectionIndex 
                                                            forChangeType:(NSFetchedResultsChangeType)type {

    switch(type) {

        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

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


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
// The fetch controller has sent all current change notifications, so tell the table view to process all updates.
    [self.tableView endUpdates];
}

Answer 1

..有点迟到的答案，但有这个错误消息＆＃34; NSInvalidArgumentException - deleteObject：需要一个非零参数＆＃34;刚刚。当我快速删除主 - 详细信息表视图中的项目并双击删除按钮时，就会发生这种情况。解决我的问题的方法是在调用deleteObject之前检查indexPath是否为nil：

    if (indexPath == nil) return;
    [context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];

Answer 2

也许可行。

在clickedButtonAtIndex方法中重置布尔值

if(toDelete == YES)
{
   // other code here...

   toDelete = NO;
}

关于您的代码的一些注释。

如果这不能解决错误，可能会尝试清除您的问题以仅突出显示关键点。

希望它有所帮助。

Answer 3

在我看来，你在两个不同的地方呼叫-deleteObject。因此，第二次尝试删除已删除的对象时可能会抛出错误（NSInvalidArgumentException -deleteObject: requires a non-nil argument）。

UITableView中的deleteObject错误，无法复制

3 个答案: