How to dynamically set background color for UITableView section headers?

Question

I'm working on implementing UITableView section headers similar to the Photos app on iPhone. The top header view should have a grey background and the other header views should have a white background. Based on that I have a couple of questions I need help with:

1. How do I find out which section header is on top (e.g. adjacent to the nav bar)? Note, that the navigation bar is translucent (meaning it displays cells below itself), so I can't go by finding visible cells and then retrieving section based on that.

2. What should be the approach to change background color of the top section header to a different color and then back to the original color when it's no longer a top one?

Answer 1

Make the property NSUInteger sectionPath and initialize it with 0 in viewDidLoad.

Create a headerView and for specific section change backgroundColor of that view.

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
     UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.frame.size.width, 30)];

    UILabel *headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, headerView.frame.size.width, headerView.frame.size.height)];

    headerLabel.textAlignment = NSTextAlignmentCenter;
    headerLabel.text = [titleArray objectAtIndex:section];

    if(section == sectionPath) {
        headerLabel.backgroundColor = [UIColor grayColor];
    }
    else {
        headerLabel.backgroundColor = [UIColor whiteColor];
    }

    [headerView addSubview:headerLabel];    

    return headerView;
}

To dynamically find the top-most header in UITableView during scrolling

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    for (NSIndexPath* i in [yourTableViewName indexPathsForVisibleRows]) {
      sectionPath = [i indexAtPosition:0];
    }
}