I think you have to traverse the fetched results controller sections and find a matching section for the given title, for example:
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
NSInteger section = 0;
for (id <NSFetchedResultsSectionInfo> sectionInfo in [_fetchedResultsController sections]) {
if ([sectionInfo.indexTitle compare:title] >= 0)
break;
section++;
}
return section;
}
For section index titles that to not have a matching section, you have to decide if you want to jump to a "lower" or "higher" section. The above method jumps to the next higher section.