Calculating multiline text height for UILabel/UITableViewCell: different results when calculating vs actual drawing

Question

This general topic has been asked here multiple times: how to render UITableViewCells with varying amount of text and thus varying height. The canonical answer is: you calculate

Answer 1

 titleSize = [title sizeWithFont:[UIFont systemFontOfSize:(CGFloat)17.0]
                                constrainedToSize:CGSizeMake(280, 2000)
                                    lineBreakMode:NSLineBreakByWordWrapping];