动态调整 UITableViewCell高度

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *cellIdentifier = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (cell == nil)
    {
        cell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier] autorelease];
        
        UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];
        label.tag = 1;
        label.lineBreakMode = NSLineBreakByWordWrapping;
        label.highlightedTextColor = [UIColor whiteColor];
        label.numberOfLines = 0;
        label.opaque = NO; // 选中Opaque表示视图后面的任何内容都不应该绘制
        //label.backgroundColor = [UIColor clearColor];
        label.backgroundColor = [UIColor redColor];
        [cell.contentView addSubview:label];
        [label release];
    }
    
    UILabel *label = (UILabel *)[cell viewWithTag:1];
    label.text = "text\n说话不算话\nobjective";
    
    //===== 设置 Label间距和 Cell高度 =====
    static const NSUInteger DEFAULT_ROW_HEIGHT = 44;//默认行高
    static const NSUInteger INTERVAL_X_Y = 2;//四边间距，正数则向内缩进
    //设置 Label间距
    CGRect cellFrame = [cell frame];
    cellFrame.origin = CGPointMake(0, 0);
    CGRect labelFrame = CGRectInset(cellFrame, INTERVAL_X_Y, INTERVAL_X_Y);
    label.frame = labelFrame;
    [label sizeToFit];
    //设置 Cell高度
    if (label.frame.size.height > (DEFAULT_ROW_HEIGHT + INTERVAL_X_Y))
    {
        cellFrame.size.height = label.frame.size.height + INTERVAL_X_Y + INTERVAL_X_Y;
    }
    [cell setFrame:cellFrame];
    //===== 设置 Label间距和 Cell高度 =====
    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [self tableView:tableView cellForRowAtIndexPath:indexPath];
    return cell.frame.size.height;
}