Question

I’m having a very common problem that I don’t know how to fix for myself, even after reading a bunch of similar posts, since making my cells non-reusable is not an option (the app slows down immensely).

The Problem

When I have 6 or more cells (maximum of 16), the contents of the first 5 cells begin appearing in all of the other cells when I scroll to them.

Though I am using reusable cells, why are the contents of my cells not being refreshed with new data that’s stored in my NSMutableArrays?

The Code

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

    WorldClockTableViewCell *worldClockCell = (WorldClockTableViewCell*)[tableView dequeueReusableCellWithIdentifier:kCellID];
if(worldClockCell == nil) {

    NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"WorldClockTableViewCell" owner:self options:nil];
    worldClockCell = [topLevelObjects objectAtIndex:0];

    /*
     Set Scrolling to OFF by default. 
     User can scroll when table is in edit mode.
     */
    [worldClockCell.scrollView setScrollEnabled:NO];

    // Set Digital Clock in timeLabel
    [self setDigitalClockInLabel:worldClockCell inRow:indexPath.row];

    // Set Analog Clock Carousel in ScrollView in every cell.
    [self setAnalogClocksInScrollView:worldClockCell inRow:indexPath.row];

    // Scroll to User's Preferred Clock (if this is the first launch of WorldClockTableViewController)
    if([[shouldAutoScrollArray objectAtIndex:indexPath.row] boolValue] == YES) {

        [self scrollToUsersPreferredClock:worldClockCell atRow:indexPath.row];
        [shouldAutoScrollArray replaceObjectAtIndex:indexPath.row withObject:[NSNumber numberWithBool:NO]];

    }   

    // Add City Name to cityLabel in every cell
    [worldClockCell buildFormattedCityName:[model.timeZoneCityNames objectAtIndex:indexPath.row]];

    // Make sure new clocks created while in 'edit' mode don't scroll out of the cell
    worldClockCell.scrollView.frame = worldClockCell.scrollViewFrame;


} 

return worldClockCell;
}

Answer 1

You’re doing all your cell configuration only if it created a new cell, not if it dequeued one. Pull everything out of

if(worldClockCell == nil)

except

NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"WorldClockTableViewCell" owner:self options:nil];
worldClockCell = [topLevelObjects objectAtIndex:0];

unless you really only need to do it once, when the cell is created (and not every time it’s reconfigured to display new data).