How to change table view center label highlighted? - iphone

Question

Table view center cell always highlight like a picker. If I select the center cell, that value is return. If I scroll the table at the time center point must highlighted the values only change(like picker action)How to do this? Any sample code for this task. Thanks in advance.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
UILabel *modelLabel;
UIButton *modelButton;
modelButton = [UIButton buttonWithType:UIButtonTypeCustom];
modelButton.frame = CGRectMake(0.0, 0.0, LABEL_WIDTH, LABEL_HEIGHT);
modelButton.tag = indexPath.row+100;
[modelButton addTarget:nil action:#selector(modelButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[[cell contentView] addSubview:modelButton];
modelLabel = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, LABEL_WIDTH, LABEL_HEIGHT)];
modelLabel.text = [NSString stringWithFormat:#"%#", [[modelArray objectAtIndex:indexPath.row] valueForKey:#"Model"]];
modelLabel.tag = indexPath.row+1000;
modelLabel.backgroundColor = [UIColor clearColor];
modelLabel.textColor = [UIColor grayColor];
modelLabel.alpha = 0.5;
modelLabel.textAlignment = UITextAlignmentCenter;
modelLabel.font = EUROSLITE_FONT(14);
[[cell contentView] addSubview:modelLabel];
}
return cell;
}
The rows count is 700, 800, like this.

Answer 1

A UITableView extends UIScrollView. So you can implement the following delegate:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
There you can check the scrollView.contentOffset and set the corresponding cell to highlighted. Please note, that's not the center cell. You need to add (int)(scrollView.frame.size.height/2)-(int)(cell.frame.size.height/2) on scrollView.contentOffset.y.
Example (Please de-highlight all other cells):
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
[[tableView visibleCells] makeObjectsPerformSelector:#selector(setHighlighted:) withObject:[NSNumber numberWithBool:NO]];
CGPoint center = CGPointMake(0, scrollView.contentOffset.y+(int)(scrollView.frame.size.height/2));
NSIndexPath *cellIndexPath = [tableView indexPathForRowAtPoint:center];
UITableViewCell *cell = [tableView cellForRowAtIndexPath:cellIndexPath];
[cell setHighlighted:YES];
}