objective-c - 保存 UITableView 单元格附件的状态？

Question

我在我的表格 View 上设置了手势识别器。

• 向右滑动，附件变为勾号图像
• 向左滑动，变成人字形图片

如果点击一个单元格，它会加载一个本地 HTML 文件。

如果您向右滑动，勾号会按原样出现。但是，如果您随后点击一个单元格以查看 HTML 文件并返回到表格 View ，图像将恢复为人字形。

确保滴答声保持其应有状态的最佳方法是什么？

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编辑

更多代码:

来自“viewDidLoad”:

UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self
                                                                                 action:@selector(handleSwipeRight:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
[self.tableView addGestureRecognizer:recognizer];

recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self
                                                       action:@selector(handleSwipeLeft:)];
//recognizer.delegate = self;
[recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
[self.tableView addGestureRecognizer:recognizer];


- (void)handleSwipeLeft:(UISwipeGestureRecognizer *)gestureRecognizer
{
//Get location of the swipe
CGPoint location = [gestureRecognizer locationInView:self.tableView];

//Get the corresponding index path within the table view
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:location];

//Check if index path is valid
if(indexPath)
{
    //Get the cell out of the table view
    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];

    //Update the cell or model

    cell.accessoryView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"disclosure.png"]];
}
}

- (void)handleSwipeRight:(UISwipeGestureRecognizer *)gestureRecognizer
{
CGPoint location = [gestureRecognizer locationInView:self.tableView];

NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:location];

if(indexPath)
{
    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];

    // cell.accessoryType = UITableViewCellAccessoryCheckmark;
    cell.accessoryView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"tick.png"]];
}

}

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

static NSString *simpleTableIdentifier = @"MFGCell";

MFGCell *cell = (MFGCell *) [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];

if (cell == nil) {
    NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"MFGCell" owner:self options:nil];
    cell = [nib objectAtIndex:0];
}

cell.itemTitle.text = [item objectAtIndex:indexPath.row];
cell.itemDescription.text = [description objectAtIndex:indexPath.row];
cell.itemImageView.image = [UIImage imageNamed:[icons objectAtIndex:indexPath.row]];

return cell;
}

Answer 1

为了响应用户的滑动，您应该存储用户的选择(例如，在 NSMutableArray 类型的私有(private)实例变量中)。当用户返回到表格 View 时，您可以重新使用 tableView:cellForRowAtIndexPath: 中的信息，以使用正确的附件样式设置单元格。

属性声明:

@property(nonatomic, retain) NSMutableArray* _accessoryStyle;

综合属性。然后将此代码段添加到 handleSwipeLeft: 的底部以存储用户的选择:

- (void)handleSwipeLeft:(UISwipeGestureRecognizer *)gestureRecognizer
{
  [...]
  NSNumber* number = [numberWithInt:0];
  [_accessoryStyle replaceObjectAtIndex:indexPath.row withObject:number];
}

在 handleSwipeRight: 的底部添加一个类似的片段:

- (void)handleSwipeRight:(UISwipeGestureRecognizer *)gestureRecognizer
{
  [...]
  NSNumber* number = [numberWithInt:1];
  [_accessoryStyle replaceObjectAtIndex:indexPath.row withObject:number];
}

在 tableView:cellForRowAtIndexPath: 中:

NSString* accessoryImageName;
NSNumber* number = [_accessoryStyle objectAtIndex:indexPath.row];
switch ([number intValue])
{
  case 0:
    accessoryImageName = @"disclosure.png";
    break;
  case 1:
    accessoryImageName = @"tick.png";
    break;
  default:
    // replace with your error handling code
    return nil;
}
cell.accessoryView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:accessoryImageName]];

要使所有这些工作正常，您需要使用与您希望表格 View 具有单元格的元素数量相同的元素来初始化 _accessoryStyle 数组。例如，在您的 View Controller 的 viewDidLoad 中:

- (void) viewDidLoad
{
  [super viewDidLoad];

  self._accessoryStyle = [NSMutableArray arrayWithCapacity:0];
  NSNumber* defaultAccessoryStyle = [numberWithInt:0];
  int numberOfRows = 17;  // get the real number from somewhere
  for (int index = 0; index < numberOfCells; ++index)
    [_accessoryStyle addObject:defaultAccessoryStyle];
}

为了平衡这一点，您需要添加

- (void) viewDidUnload
{
  [super viewDidUnload];
  self._accessoryStyle = nil;
}

还有很大的改进空间:

• 找到更好的变量名
• 对不同的样式使用枚举，而不仅仅是硬编码数字 0 和 1
• 不要为每个表格 View 单元格分配一个新的UIImageView，只分配其中两个并根据附件样式使用正确的一个