detect which section of UITableview \nFrom http://transoceanic.blogspot.com/2012/08/objective-c-uitableview-detect-which.html

detect.m

static NSInteger currentTopVisibleSection = -1;
 
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
    NSIndexPath *topCellPath = [[tableView indexPathsForVisibleRows] objectAtIndex:0];
    if (currentTopVisibleSection != topCellPath.section) {
        currentTopVisibleSection = topCellPath.section;
        NSLog(@"current section on top is %d", currentTopVisibleSection);
    }
 
    NSString *header = [NSString stringWithFormat:@"Section %d", section];
    return header;
}