The best way to do this is to add a dummy cell below the cell that was tapped.

First you need to keep track of what cell is been tapped and act accordingly.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

    //if user tapped the same row twice let's start getting rid of the control cell
    if([indexPath isEqual:self.tappedIndexPath]){
        [tableView deselectRowAtIndexPath:indexPath animated:NO];
    }

    //update the indexpath if needed... I explain this below 
    indexPath = [self modelIndexPathforIndexPath:indexPath];

    //pointer to delete the control cell
    NSIndexPath *indexPathToDelete = self.controlRowIndexPath;

    //if in fact I tapped the same row twice lets clear our tapping trackers 
    if([indexPath isEqual:self.tappedIndexPath]){
        self.tappedIndexPath = nil;
        self.controlRowIndexPath = nil;
    }
    //otherwise let's update them appropriately 
    else{
        self.tappedIndexPath = indexPath; //the row the user just tapped. 
        //Now I set the location of where I need to add the dummy cell 
        self.controlRowIndexPath = [NSIndexPath indexPathForRow:indexPath.row + 1   inSection:indexPath.section];
    }

    //all logic is done, lets start updating the table
    [tableView beginUpdates];

    //lets delete the control cell, either the user tapped the same row twice or tapped another row
    if(indexPathToDelete){
        [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPathToDelete] 
                          withRowAnimation:UITableViewRowAnimationNone];
    }
    //lets add the new control cell in the right place 
    if(self.controlRowIndexPath){
        [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:self.controlRowIndexPath] 
                          withRowAnimation:UITableViewRowAnimationNone];
    }

    //and we are done... 
    [tableView endUpdates];  
} 

Whenever you have that dummy cell present you have to make sure to send the correct count.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if(self.controlRowIndexPath){
        return modelArray.count + 1;
    }
    return self.modelArray.count;
}

Also, return the appropriate height for your ControlCell.

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath   *)indexPath 
{
    if([indexPath isEqual:self.controlRowIndexPath]){
        return 45; //height for control cell
    }
    return 70; //height for every other cell 
}

Lastly, remember the control cell is a dummy. Is not part of the model, thus you have to account for that. If the user taps a row that is above the last tapped row is ok but when the new tapped row is below that control cell you have to make sure you access the right row in your model. In other words, account for that fake cell in the middle of your view.

- (NSIndexPath *)modelIndexPathforIndexPath:(NSIndexPath *)indexPath
{
    int whereIsTheControlRow = self.controlRowIndexPath.row;
    if(self.controlRowIndexPath != nil && indexPath.row > whereIsTheControlRow)
        return [NSIndexPath indexPathForRow:indexPath.row - 1 inSection:0]; 
    return indexPath;
}
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