Using UITableViewCell with dynamic height & autolayout

TableViewCellWithAutoLayout.m

// https://github.com/smileyborg/TableViewCellWithAutoLayout/blob/master/TableViewCellWithAutoLayout/TableViewController/RJTableViewController.m
// http://stackoverflow.com/a/18746930/123781

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // This project has only one cell identifier, but if you are have more than one, this is the time
    // to figure out which reuse identifier should be used for the cell at this index path.
    NSString *reuseIdentifier = CellIdentifier;
    
    // Use the dictionary of offscreen cells to get a cell for the reuse identifier, creating a cell and storing
    // it in the dictionary if one hasn't already been added for the reuse identifier.
    // WARNING: Don't call the table view's dequeueReusableCellWithIdentifier: method here because this will result
    // in a memory leak as the cell is created but never returned from the tableView:cellForRowAtIndexPath: method!
    RJTableViewCell *cell = [self.offscreenCells objectForKey:reuseIdentifier];
    if (!cell) {
        cell = [[RJTableViewCell alloc] init];
        [self.offscreenCells setObject:cell forKey:reuseIdentifier];
    }
    
    // Configure the cell for this indexPath
    [cell updateFonts];
    NSDictionary *dataSourceItem = [self.model.dataSource objectAtIndex:indexPath.row];
    cell.titleLabel.text =  [dataSourceItem valueForKey:@"title"];
    cell.bodyLabel.text = [dataSourceItem valueForKey:@"body"];
    
    // Make sure the constraints have been added to this cell, since it may have just been created from scratch
    [cell setNeedsUpdateConstraints];
    [cell updateConstraintsIfNeeded];
    
    // The cell's width must be set to the same size it will end up at once it is in the table view.
    // This is important so that we'll get the correct height for different table view widths, since our cell's
    // height depends on its width due to the multi-line UILabel word wrapping. Don't need to do this above in
    // -[tableView:cellForRowAtIndexPath:] because it happens automatically when the cell is used in the table view.
    cell.bounds = CGRectMake(0.0f, 0.0f, CGRectGetWidth(tableView.bounds), CGRectGetHeight(cell.bounds));
    // NOTE: if you are displaying a section index (e.g. alphabet along the right side of the table view), or
    // if you are using a grouped table view style where cells have insets to the edges of the table view,
    // you'll need to adjust the cell.bounds.size.width to be smaller than the full width of the table view we just
    // set it to above. See http://stackoverflow.com/questions/3647242 for discussion on the section index width.
    
    // Do the layout pass on the cell, which will calculate the frames for all the views based on the constraints
    // (Note that the preferredMaxLayoutWidth is set on multi-line UILabels inside the -[layoutSubviews] method
    // in the UITableViewCell subclass
    [cell setNeedsLayout];
    [cell layoutIfNeeded];
    
    // Get the actual height required for the cell
    CGFloat height = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
    
    // Add an extra point to the height to account for the cell separator, which is added between the bottom
    // of the cell's contentView and the bottom of the table view cell.
    height += 1;
    
    return height;
}