iphone - 从 MutableArray 加载的 UITableView 变成一个复选框列表

Question

我有一个 TableView ，它是从下面列出的可变数组加载的。但是我需要为数组中的每个项目分配一个 ID 并在项目旁边有一个复选框。基本上它是我们搜索的偏好，它让用户根据勾选的复选框确定优先级。所以我想保存哪些项目被勾选到 plist 或类似的。

数组的加载方式如下:

arryTableIconsText =     [[NSMutableArray alloc] init]; 

[arryTableIconsText addObject:@"Facilities for partially sighted or blind people"];
[arryTableIconsText addObject:@"An 'assistance dogs welcome' policy"];
[arryTableIconsText addObject:@"Disabled access facilities for wheelchair users (with assistance)"];
*more items added here*

arryTableIcons = [[NSMutableArray alloc] init];

[arryTableIcons addObject:@"visuallyImpaired_off.png"];
[arryTableIcons addObject:@"guidedogs_off.png"];
[arryTableIcons addObject:@"wheelchairassist_off.png"];
    *more items added here*

然后像这样加载到表中:

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

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
    }

    cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
    cell.textLabel.numberOfLines = 0;
    cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:17.0];

    cell.textLabel.text = [arryTableIconsText objectAtIndex:indexPath.row];
    cell.imageView.image = [UIImage imageNamed:[arryTableIcons objectAtIndex:indexPath.row]];   

    return cell;
}

结果如下:

但我不知道从这里到哪里才能将其转换为保存 ID 的每个单元格右侧的复选框？

任何提示真的会很感激，汤姆

Answer 1

使用 NSMutableIndexSet 实例变量并用被检查的单元格的索引填充它。

然后在 cellForRowAtIndexPath 方法中，将单元格的附件类型设置为 UITableViewCellAccessoryTypeCheckmark 或 UITableViewCellAccessoryTypeNone ，具体取决于 indexPath.row 所在的位置NSMutableIndexSet 与否。

最后，当单元格被点击时，如果 indexPath.row 还没有被添加到索引集中，或者如果它已经存在则将其删除，以切换相应单元格的状态，然后调用 reloadData 在 tableView 上。

我在你的代码中也看到你不熟悉 UITableViewCells 的重用机制。您应该阅读 Apple 文档中的“Table View Programming Guide”并学习如何以更高效和 react 性的方式(在 react 性和内存占用方面)实现 cellForRowAtIndexPath

---

例子

// Let selectedCellIndexes be an instance variable in your .h of type NSMutableIndexSet*
// Initialize it (probably at the same place you initialise your texts & icons, once for all, probably in your init method
selectedCellIndexes = [[NSMutableIndexSet alloc] init];

然后填充单元格:

-(UITableViewCell*)tableView:(UITableView*)tv cellForRowAtIndexPath:(NSIndexPath*)indexPath {
  // Try to recycle and already allocated cell (but not used anymore so we can reuse it)
  UITableViewCell* cell = [tv dequeueCellWithReuseIdentifier:...];
  if (cell == nil) {
    // If we didn't manage to get a reusable (existing) cell to recycle it
    // then allocate a new one and configure its general properties common to all cells
    cell = [[[UITableViewCell alloc] initWithStyle:... reuseIdentifier:...] autorelease];

    // ... configure stuff that are common to all your cells : lineBreakMode, numberOfLines, font... once for all
    cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
    cell.textLabel.numberOfLines = 0;
    cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:17.0];
  }

  // Then here change the stuff that are different between each cell
  // (this code will be executed if the cell has just been allocated as well as if the cell is an old cell being recycled)
  cell.textLabel.text = [arryTableIconsText objectAtIndex:indexPath.row];
  cell.imageView.image = [UIImage imageNamed:[arryTableIcons objectAtIndex:indexPath.row]];
  cell.accessoryType = [selectedCellIndexes containsIndex:indexPath.row] ? UITableViewCellAccessoryTypeCheckmark : UITableViewCellAccessoryTypeNone;

  return cell;
}

最后，切换复选标记:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
  if ([selectedCellIndexes containsIndex:indexPath.row]) {
    [selectedCellIndexes removeIndex:indexPath.row];
  } else {
    [selectedCellIndexes addIndex:indexPath.row];
  }
  [tableView reloadData];
}