How to hide first section header in UITableView (grouped style)

As the design of table views using the grouped style changed considerably with iOS 7, I would like to hide (or remove) the first section header. So far I haven't managed to achieve it.

Somewhat simplified, my code looks like this:

- (CGFloat) tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    if (section == 0)
        return 0.0f;
    return 32.0f;
}

- (UIView*) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    if (section == 0) {
        UIView* view = [[UIView alloc] initWithFrame: CGRectMake(0.0f, 0.0f, 640.0f, 0.0f)];
        return view;
    }
    return nil;
}

- (NSString*) tableView:(UITableView *) tableView titleForHeaderInSection:(NSInteger)section
{
    if (section == 0) {
        return nil;
    } else {
        // return some string here ...
    }
}

If I return a height of 0, the other two methods will never be called with the section index 0. Yet an empty section header is still drawn with the default height. (In iOS 6, the two methods are called. However, the visible result is the same.)

If I return a different value, the section header gets the specified height.

If I return 0.01, it's almost correct. However, when I turn on "Color Misaligned Images" in the simulator, it marks all table view cells (which seems to be a logical consequence).

The answers to the question UITableView: hide header from empty section seem to indicate that some people were successful in hiding the section header. But it might apply to the plain style (instead of the grouped one).

The best compromise so far is returning the height 0.5, resulting in a somewhat thicker line below the navigation bar. However, I'd appreciate if somebody knows how the first section header can be completely hidden.

Update

According to caglar's analysis (https://stackoverflow.com/a/19056823/413337), the problem only arises if the table view is contained in a navigation controller.

I have a workaround that seems reasonably clean to me. So I'm answering my own question.

Since 0 as the first section header's height doesn't work, I return 1. Then I use the contentInset to hide that height underneath the navigation bar.

Objective-C:

- (CGFloat) tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    if (section == 0)
            return 1.0f;
    return 32.0f;
}

- (NSString*) tableView:(UITableView *) tableView titleForHeaderInSection:(NSInteger)section
{
    if (section == 0) {
        return nil;
    } else {
        // return some string here ...
    }
}

- (void) viewDidLoad
{
    [super viewDidLoad];

     self.tableView.contentInset = UIEdgeInsetsMake(-1.0f, 0.0f, 0.0f, 0.0);
}

Swift:

override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return section == 0 ? 1.0 : 32
}

override func viewDidLoad() {
    super.viewDidLoad()

    tableView.contentInset = UIEdgeInsets(top: -1, left: 0, bottom: 0, right: 0)
}

This is how to hide the first section header in UITableView (grouped style).

Swift 3.0 & Xcode 8.0 Solution

1. The TableView's delegate should implement the heightForHeaderInSection method

2. Within the heightForHeaderInSection method, return the least positive number. (not zero!)

   func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
   
       let headerHeight: CGFloat
   
       switch section {
       case 0:
           // hide the header
           headerHeight = CGFloat.leastNonzeroMagnitude
       default:
           headerHeight = 21
       }
   
       return headerHeight
   }
   

The answer was very funny for me and my team, and worked like a charm

• In the Interface Builder, Just move the tableview under another view in the view hierarchy.

REASON:

We observed that this happens only for the First View in the View Hierarchy, if this first view is a UITableView. So, all other similar UITableViews do not have this annoying section, except the first. We Tried moving the UITableView out of the first place in the view hierarchy, and everything was working as expected.

Use this trick for grouped type tableView

Copy paste below code for your table view in viewDidLoad method:

tableView.tableHeaderView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, tableView.bounds.size.width, 0.01f)];

this way is OK.

override func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    if section == 0 {
        return CGFloat.min
    }
    return 25
}

override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    if section == 0 {
        return nil
    }else {
        ...
    }
}