UICollectionView：消除单元格问题

Question

I am trying to remove a cell from my collectionView, however. When I remove the object from my datasource and attempt a batchupdate, it says the cell doesn't exist anymore.:

'NSInternalInconsistencyException', reason: 'attempt to delete item 0 from section 0 which only contains 0 items before the update'

Before this code I remove the content from my core data, and the line [[usermanager getSelectedUser]loadCards]; actually reloads the datasource containing the content for the cells by getting them from the Core Data.

- (void)cardRemoved:(NSNotification *)note {

    NSDictionary *args = [note userInfo];
    Card *card = [args objectForKey:@"card"];
    [[usermanager getSelectedUser]loadCards];
    [self.collectionView performBatchUpdates:^{
        NSIndexPath *indexPath =[NSIndexPath indexPathForRow:card.position.intValue inSection:0];
        [self.collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
    } completion:^(BOOL finished){
        [self.collectionView setDelegate:self];
        [self.collectionView setDataSource:self];
        [self.collectionView reloadData];

    }];
}

If I print out the amount of Cells before I call the loadCards line, I get the correct amount of rows(As expected).

EDIT This is what loadCards calls:

-(NSMutableArray *)getCards{
    UserModel *selectedUser = [self getSelectedUserFromDB];
    NSMutableArray *cards = [[NSMutableArray alloc] init];
    for(CardModel *cardModel in selectedUser.cards){
        [cards addObject:[self modelToCard:cardModel]];
    }
    return cards;
}

I noticed, even if I don't call the loadCards method, It says there are no items in the view.

Can anyone help me out? Thank you

Answer 1

Remove the cells from the UICollectionView , then remove them from the model. The same thing applies to UITableView . You also don't need to reload the collection view after removing items.

If you prefer you can just remove items from the model and then reload the collection view and the items that aren't in the model will disappear from the collection view, but without the same animation that comes from removing items from a collection view.