ios - dequeueReusableCellWithIdentifier 不释放数据

Question

我有一个 UITableView，一旦它滚出屏幕，它就不会释放它显示的数据。

每个表格单元格都需要显示名称、日期和图片。第一个充满屏幕的单元格在启动时可以正常工作，因为它们没有被重复使用。然而，一旦您开始滚动并且单元格被重复使用，显示的数据就会堆叠在该单元格之前存储的内容上(例如:日期将在 1972 年 12 月 15 日之上堆叠 1981 年 7 月 4 日)。

这是我的代码:

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.title = @"";

    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:kTableViewCellIdentifier];

    self.nameArray = @[@"list of names"];
    self.dateArray = @[@"list of dates"];
    self.imageArray = @[@"list of images"];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return  [self.nameArray count];
}


- (UIView *)messageFeed:(NSIndexPath *)indexPath
{
    UIView *feedView = [[UIView alloc] init];
    //...feedView attributes

    UILabel *nameLabel = [[UILabel alloc]initWithFrame:CGRectMake(..., ..., ..., ...)];
    nameLabel.text = self.nameArray[indexPath.row];
    //nameLabel attributes

    UILabel *dateLabel = [[UILabel alloc] initWithFrame:CGRectMake(..., ..., ..., ...)];
    dateLabel.text = self.dateArray[indexPath.row];
    //dateLabel attributes

    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(..., ..., ..., ...)];
    imageView.image = [UIImage imageNamed: self.imageArray[indexPath.row]];
    //imageView attributes

    [feedView addSubview:nameLabel];
    [feedView addSubview:dateLabel];
    [feedView addSubview:imageView];

    return feedView;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kTableViewCellIdentifier forIndexPath:indexPath];

    // Configure the cell...

    [cell addSubview:[self messageFeed:indexPath]];

    return cell;
}

Answer 1

不确定这是否是最佳解决方案，但这对我有用。当我需要将 UI 字段添加到单元格 subview 时，单元格似乎并不总是 nil 为了解决这个问题，我首先检查是否设置了任何单元格标签。如果不是，我将所有 UI 字段添加回单元格 subview 。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath    
{
   UILabel *background;
   UILabel *nameLabel;
   UILabel *dateLabel;
   UIImageView *imageView;

   UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kTableViewCellIdentifier];

   if (cell == nil) {
       cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kTableViewCellIdentifier];
   }

   background = (UILabel *) [cell viewWithTag:1];
   if (!background) {
       cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
       background = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 40.0f)];
       background.backgroundColor = [UIColor lightGrayColor];
       background.tag = 1;
      [cell.contentView addSubview:background];

      nameLabel = [[UILabel alloc]initWithFrame:CGRectMake(84.0f, 10.0f, 216.0f, 29.0f)];
      nameLabel.textColor = [UIColor blackColor];
      nameLabel.font = [UIFont boldSystemFontOfSize:20.0f];
      nameLabel.tag = 2;
      [cell.contentView addSubview:nameLabel];

      dateLabel = [[UILabel alloc] initWithFrame:CGRectMake(84.0f, 40.0f, 216.0f, 21.0f)];
      dateLabel.textColor = [UIColor blackColor];
      dateLabel.font = [UIFont systemFontOfSize:10.0f];
      dateLabel.tag = 3;
      [cell.contentView addSubview:dateLabel];

      imageView = [[UIImageView alloc]initWithFrame:CGRectMake(20.0f, 13.0f, 56.0f, 51.0f)];
      imageView.tag = 4;
      [cell addSubview:imageView];
   } else {
      nameLabel = (UILabel *) [cell viewWithTag:2];
      dateLabel = (UILabel *) [cell viewWithTag:3];
      imageView = (UIImageView *) [cell viewWithTag:4];
   }

   nameLabel.text = self.nameArray[indexPath.row];
   dateLabel.text = self.dateArray[indexPath.row];
   imageView.image = [UIImage imageNamed: self.imageArray[indexPath.row]];

   return cell;

}