sorting an array of PFObjects by username

Question

I have an array of PFUsers and I'm trying to filter them based on local search results:

- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
    NSPredicate *resultPredicate = [NSPredicate
                                    predicateWithFormat:@"username contains[cd] %@",
                                    searchText];

    _searchResults = [[_messages filteredArrayUsingPredicate:resultPredicate] mutableCopy];
    NSLog(@"_searchResults: %@",_searchResults);
}

But this doesn't work and ends up producing the following error:

'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:'

Does anybody know what's wrong with my NSPredicate? Thank you!

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell;

    if (cell == nil) {
       cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    }

    if (tableView == self.searchDisplayController.searchResultsTableView) {
        NSLog(@"here?");
        cell.textLabel.text = [_searchResults objectAtIndex:indexPath.row];
    } else {


        UILabel *name = (UILabel *)[cell viewWithTag:101];
        if (_messages.count == 0)
            name.text = @"No Messages";
        else
            name.text = @"name";
    }

    return cell;
}

I don't think the NSPredicate filter is working though...

I guess it is not NSPredicate error, Can you show your tableView:cellForRowAtIndexPath method? — Toseef Khilji
– Toseef Khilji, Commented Jan 28, 2014 at 4:19
You are not providing nearly enough information. You posted a block of code that filters an array into a results array. How does that relate to your table view data source? You need to provide a lot more information about what you're doing, and especially, post your cellForRowAtIndexPath method, as @Virussmca says. — Duncan C
– Duncan C, Commented Jan 28, 2014 at 4:26
try to NSlog the _searchResults array in the cellForRowAtIndexPath method and use breakpoints to prevent app from crashing. — GoGreen
– GoGreen, Commented Jan 28, 2014 at 11:39
@GoGreen I am doing that and the _search results array never contains anything... — Apollo
– Apollo, Commented Jan 28, 2014 at 14:38
what about the same _searchResults array in filterContentForSearchText:scope: ? does it contain any value there? If no, then are you sure you have a user with the same character sequence as the searchText ? — GoGreen
– GoGreen, Commented Jan 28, 2014 at 14:56

b_s · Accepted Answer · 2014-02-18 07:28:04Z

1

The issue is not with your NSPredicate but rather the fact that - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath is not returning a cell.

This block of code attempts to dequeue a reusable cell if the "cell" = nil. In this case a new cell is never actually created so attempting to dequeue an existing cell will always return nil.

  if (cell == nil) {
   cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
}

Instead you need to check if there is an existing cell available for reuse and if not create a new one.

cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}

answered Feb 18, 2014 at 7:28

b_s

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