Iphone - when to calculate heightForRowAtIndexPath for a tableview when each cell height is dynamic?

Question

I have seen this question asked many times but astoundingly, I have not seen a consistent answer, so I will give it a try myself:

If you have a tableview containing

Answer 1

This is how I calculate the height of a cell based on the amount of text in a UTextView:

#define PADDING  21.0f

- (CGFloat)tableView:(UITableView *)t heightForRowAtIndexPath:(NSIndexPath *)indexPath {

    if(indexPath.section == 0 && indexPath.row == 0)
    {   
        NSString *practiceText = [practiceItem objectForKey:@"Practice"];
        CGSize practiceSize = [practiceText sizeWithFont:[UIFont systemFontOfSize:14.0f] 
                   constrainedToSize:CGSizeMake(tblPractice.frame.size.width - PADDING * 3, 1000.0f)];
        return practiceSize.height + PADDING * 3;
    }

    return 72;
}

Of course, you would need to adjust the PADDING and other variables to fit your needs, but this sets the height of the cell which has a UITextView in it, based on the amount of text supplied. so if there are only 3 lines of text, the cell is fairly short, where as if there are 14 lines of text, the cell is rather large in height.