我应该如何将子视图添加到cell.contentView？

问题描述：

A（当新创建单元格时）：

A (when the cell is newly created):

- (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];

        CGRect frame = CGRectMake(0, 0, 160, 50);
        UILabel *label = [[UILabel alloc] initWithFrame:frame];
        label.textAlignment = UITextAlignmentRight;
        label.text = @"9:00am";
        [cell.contentView addSubview:label];
        [label release];
    }

    return cell;
}

或B（每次找到单元格时）：

or B (every time when the cell is found):

- (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];    
    }

    CGRect frame = CGRectMake(0, 0, 160, 50);
    UILabel *label = [[UILabel alloc] initWithFrame:frame];
    label.textAlignment = UITextAlignmentRight;
    label.text = @"9:00am";
    [cell.contentView addSubview:label];
    [label release];

    return cell;
}

A或B？谢谢！

更新解决方案（感谢答案）：

UPDATE Solution (thanks for the answers):

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{

    static NSString *CellIdentifier = @"Cell";    
    UILabel *label;
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];

        CGRect frame = CGRectMake(0, 0, 160, 50);
        label = [[UILabel alloc] initWithFrame:frame];
        label.textAlignment = UITextAlignmentRight;
        label.tag = 1;
        [cell.contentView addSubview:label];
        [label release];
    } else {
        label = (UILabel *) [cell viewWithTag:1];
    }

    label.text = [NSString stringWithFormat:@"%d", [indexPath row]];

    return cell;
}

答

这都是关于性能的。使用A，您可以重复使用包含其所有子视图的单元格，使用B，您只重用原始单元格并在每次迭代时添加新的子视图，恕我直言不如A re：performance。

It's all about performance. With A, you reuse the cell with all of its subviews, with B, you reuse only the raw cell and add a new subview every iteration, which IMHO is not as good as A re: performance.

我说创建 UITableView 子类或使用解决方案A.

I say either create a UITableView subclass or use solution A.

我应该如何将子视图添加到cell.contentView？

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