UITableView单元格附件的保存状态? [英] Saving state of UITableView cell accessory?

问题描述

我在表格视图中设置了手势识别器.

I have gesture recognisers set up on my table view.

• 向右滑动，附件将变成刻度线图像
• 向左滑动即可更改为人字形图像

如果点击一个单元格，它将加载本地HTML文件.

If a cell is tapped, it loads a local HTML file.

如果向右滑动，将显示刻度线.但是，如果您随后点击一个单元格以查看HTML文件并返回到表格视图，则图像将还原为人字形.

If you swipe to the right, the tick appears as it should. However, if you then tap a cell to view a HTML file and come back to the table view, the image reverts to the chevron.

确保刻度线保持应有的最佳方式是什么?

What's the best way to ensure the tick stays as it should?

更多代码:

来自"viewDidLoad":

From '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;
}

推荐答案

为响应用户的滑动，您应该存储用户的选择(例如，存储在 NSMutableArray 类型的私有实例变量中).当用户返回到表格视图时，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.

In reaction to the user's swipe you should store the user's choice (e.g. in a private instance variable of type NSMutableArray). When the user comes back to the table view you can then reuse the information in your tableView:cellForRowAtIndexPath: to setup the cell with the correct accessory style.

财产声明:

@property(nonatomic, retain) NSMutableArray* _accessoryStyle;

合成属性.然后将此代码段添加到 handleSwipeLeft:的底部以存储用户的选择:

Synthesize the property. Then add this snippet to the bottom of handleSwipeLeft: to store the user's choice:

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

在 handleSwipeRight::

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

在 tableView:cellForRowAtIndexPath::

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进行，您需要使用希望表视图具有单元格的元素数量相同的元素来初始化 _accessoryStyle 数组.例如，在您的视图控制器的 viewDidLoad :

For all this to work you need to initialize the _accessoryStyle array with the same number of elements that you expect your table view to have cells. For instance, in your view controller's viewDidLoad:

- (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];
}

要平衡这一点，您需要添加

And to balance this you need to add

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

还有很多改进的余地:

• 找到更好的变量名
• 对不同样式使用枚举，而不仅仅是硬编码数字0和1
• 不要为每个表视图单元格分配新的 UIImageView ，只需分配其中两个，并根据附件样式使用正确的一个即可.

• Find better variable names
• Use an enumeration for the different styles instead of just hardcoded numbers 0 and 1
• Do not allocate a new UIImageView for each table view cell, just allocate two of them and use the right one depending on the accessory style

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