How to set the UITableView Section title programmatically (iPhone/iPad)?

Once you have connected your UITableView delegate and datasource to your controller, you could do something like this:

ObjC

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {

    NSString *sectionName;
    switch (section) {
        case 0:
            sectionName = NSLocalizedString(@"mySectionName", @"mySectionName");
            break;
        case 1:
            sectionName = NSLocalizedString(@"myOtherSectionName", @"myOtherSectionName");
            break;
        // ...
        default:
            sectionName = @"";
            break;
    }    
    return sectionName;
}

Swift

func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {

    let sectionName: String
    switch section {
        case 0:
            sectionName = NSLocalizedString("mySectionName", comment: "mySectionName")
        case 1:
            sectionName = NSLocalizedString("myOtherSectionName", comment: "myOtherSectionName")
        // ...
        default:
            sectionName = ""
    }
    return sectionName
}

If you are writing code in Swift it would look as an example like this

func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String?
{
    switch section
    {
        case 0:
            return "Apple Devices"
        case 1:
            return "Samsung Devices"
        default:
            return "Other Devices"
    }
}

Use the UITableViewDataSource method

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section

titleForHeaderInSection is a delegate method of UITableView so to apply header text of section write as follows,

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
    return @"Hello World";
}

Note that -(NSString *)tableView: titleForHeaderInSection: is not called by UITableView if - (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section is implemented in delegate of UITableView;