- (void)tableView:(UITableView *)tableView didUpdateFocusInContext:(UITableViewFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator
{
     //this gives you the indexpath of the focused cell
     NSIndexPath *nextIndexPath = [context nextFocusedIndexPath];
}

NSIndexPath *nextIndexPath = [context nextFocusedIndexPath];
NSIndexPath *prevIndexPath = [context previouslyFocusedIndexPath];

UITableViewCell *nextCell = [self.tableView cellForRowAtIndexPath:nextIndexPath];
UILabel *nextTitleLabel = (UILabel *)[nextCell viewWithTag:100];
nextTitleLabel.textColor = [UIColor blackColor];

UITableViewCell *prevCell = [self.tableView cellForRowAtIndexPath:prevIndexPath];
UILabel *prevTitleLabel = (UILabel *)[prevCell viewWithTag:100];
prevTitleLabel.textColor = [UIColor whiteColor];

override func didUpdateFocus(in context: UIFocusUpdateContext, with coordinator: UIFocusAnimationCoordinator) {
  let cell = context.nextFocusedView as! UITableViewCell
  let indexPath = table.indexPath(for: cell)
}