Dynamic label height with KILabel

gistfile1.m

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row < self.timeline.count)
    {
        NSDictionary *tweet = self.timeline[indexPath.row];
        NSAttributedString *string = [TLTimelineViewController decorateLabelStringForMessage:tweet];
        
        // Measure the string, it's height is dynamic based on content. We calculate
        // a width for the string by assuming the cell will fill the width of the table
        // minus some padding applied around elements.
        enum { kHorzPadding = 56 };
        CGSize sizeForLabel = CGSizeMake(self.tableView.frame.size.width - kHorzPadding, 0);
        CGRect labelRect = CGRectMake(0, 0, sizeForLabel.width, CGFLOAT_MAX);
        
        // Use a dummy label and its textRectForBounds method to calculate the height
        // of a real label.
        static KILabel *measureLabel = nil;
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            measureLabel = [[KILabel alloc] initWithFrame:CGRectMake(0, 0, self.tableView.frame.size.width - kHorzPadding, 16)];
            measureLabel.numberOfLines = 0;
        });
        measureLabel.attributedText = string;    
        labelRect = [measureLabel textRectForBounds:labelRect limitedToNumberOfLines:0];
        
        return 48 + labelRect.size.height - 16;
    }
    else
    {
        return 44;
    }
}

This is how work out the heights of rows of KILabels in a timeline view.

The KILabel demo app now has a solution for doing this with auto layout. You no longer need to override tableView:heightForRowAtIndexPath:.