Question

I have a UITableview cell that gets a tally from a core data database. The tallyTable is in a view controller inside a UITab view. I have an NSLog statement that prints out the tally value whenever it gets updated. Another tab has a list to change the source (different day) for the tallies. I am using iOS5 with ARC targeting iOS 4.2.

Here’s the problem. When I load the application, the correct tallies for whatever the last selected day show up in the table tab. If I then go to the day tab and change the day and return to the tally tab there is no change in the display. However, the viewWillAppear on the tally tab runs and as the table cycles through cellForIndexPath, my NSLog statement prints out all the correct new values. If I then scroll the top label off the screen and back the label updates to the new value.

I’ve tried setNeedsLayout and setNeedsDisplay on the UILabel, the UITableViewCell, the UITableView and the view controller loading the table. I tried changing the CellReuse identifier so that it would never reuse a cell.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";    
    CollectionItemTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[CollectionItemTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    NSUInteger row = [indexPath row];
    cell.textLabel.text = [[self.collectionKeys objectAtIndex:row] valueForKey:@"collectionTitle"];
    NSInteger test1 = indexPath.row + 150;
    NSLog(@"tag = %i", test1);
    cell.tallyButton.tag = test1;
    NSNumber * questionID = [[self.collectionKeys objectAtIndex:row] valueForKey:@"answerID"];
    cell.tallyLabel.text = [NSString stringWithFormat:@"%i",[self updatePointTotal:questionID]];
NSLog(@"Collection text should be = %@", [NSString stringWithFormat:@"%i",[self updatePointTotal:questionID]]);

    [cell setNeedsLayout];

    return cell;
}

I’ve read over a half dozen other similar questions. Got about three hours invested so far in trying to solve this.

EDIT: I thought I fixed it by using the navigation controller to repush the top level view controller on to the view again. I’ll admit now this feels like a classically kludgy hack in every way. When the view is PUSHED everything updates and it is seamless. However, in order to have a fixed footer to make selection settings for the table buttons, I used a UIView with two subviews, a UITableView on top and a simple UIView with four buttons below.

The captions on the buttons need to change with the data source. Now when the view controller is pushed onto the view it obscures my fixed footer view. So, I inserted the fixed footer into the UITableview and everything appeared fine until I scrolled the UITableView and the footer scrolled up with it. The table is basically a tally sheet with buttons next to each item and in the footer is four buttons to note the color of the tallied item. Say the next item was a green lego, you would tap “green” in the footer and the button next to “lego” in the table. When I push the view controller with the two subviews the UITableview labels do not update. Thus the tableview needs to be pushed itself (as far as I can tell).

ANSWER: see comment below but ultimately I needed to reload both the visible UITableView data and the delegate UITableView controller data behind it.

Answer 1

I’ll give it a shot. First, are you using ARC? If not, you need to add autorelease when you alloc/init a new cell. Otherwise, it’s fine as is.

If I’m understanding your question correctly:

• The tableView displays the correct data at app launch

• You switch away from the tab with the tableView and change the tableView dataSource

• You switch back to the tab with the tableView and you see (via NSLog) that the table cells are reloaded with the correct data yet the old data is still visible in the cells

• If you scroll a cell off the display and back forcing it to refresh it contains the correct data

Some thoughts:

1. the tableView will not reload itself automatically when it’s view appears. You need to call [tableView reloadData] whenever the dataSource changes. This is independent of whether the tableView is currently displayed or not. My guess is this alone will solve your problem.

2. You don’t need to call setNeedsLayout on the cell unless you want the cell to relayout its subviews based on the data. You also don’t need setNeedsDisplay.

3. I’m assuming there aren’t other complicating factors (such as multiple tableViews displaying the same data) that could confuse things.