At heightForRowAtIndexPath
the cell will not be created. You need to measure the height of your content independent of the cell.
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
Tweet *tweet = self.tweets[indexPath.row];
CGFloat height = [tweet.text sizeWithFont:[Your Font] constrainedToSize:[CGSizeMake(Your Cell Width, CGFLOAT_MAX)];
NSURL *url = [NSURL URLWithString:[tweet imageURLFromTweet]];
UIImage *image = [Get your image and cache it so you can the set it during configureCell];
height += image.size.height;
return height;
}