Комментарий @ SoftDesigner работал для меня
CGRect descriptionRect = [description boundingRectWithSize:CGSizeMake(width, 0)
options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
attributes:@{NSFontAttributeName : [UIFont systemFontOfSize:12]}
context:nil];
result = ceil(descriptionRect.size.height);