Tableview忘记了UISegmentedControl中的selectedSegment？

Question

如果我选择了一些细分，然后向下滚动tableView，它会忘记我选择的细分？ 我究竟做错了什么？ 还是我想念什么？ 看起来每次都会重置该单元格，但是我试图删除该cell = nil; 但没有运气。 我认为可能对此产生影响的所有代码都在这里：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"FancyCell"];
cell = nil;
if (!cell) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"FancyCell"];
    cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
    // add the segmentedControl when you create a new cell
    UIImage *correctImageGreen = [[UIImage imageNamed:@"green.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UIImage *correctImageGul = [[UIImage imageNamed:@"gul.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UIImage *correctImageRed = [[UIImage imageNamed:@"red.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    NSArray *itemArray = [NSArray arrayWithObjects: correctImageGreen, correctImageGul, correctImageRed, nil];
    UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:itemArray];
    segmentedControl.frame = CGRectMake(308, 8, 150, 28);
    [cell.contentView addSubview:segmentedControl];

    // add an action so we can change our model if the view changes
    [segmentedControl addTarget:self action:@selector(didChangeSegmentedControl:) forControlEvents:UIControlEventValueChanged];

    // use a tag so we can retrieve the segmentedControl later
    segmentedControl.tag = 42;
}
// either if the cell could be dequeued or you created a new cell,
// segmentedControl will contain a valid instance
UISegmentedControl *segmentedControl = (UISegmentedControl *)[cell.contentView viewWithTag:42];

UIImage *comment = [UIImage imageNamed:@"Checkmark-hvid"];
UIImage *imageRef = [UIImage imageNamed:@"Checkmark-hvid"];
UIImageView *commentView = [[UIImageView alloc] initWithImage: comment];
UIImageView *imageRefView = [[UIImageView alloc] initWithImage: imageRef];
commentView.frame = CGRectMake(625, 5, 30, 30);
imageRefView.frame = CGRectMake(515, 5, 30, 30);
commentView.tag = 98;
imageRefView.tag = 99;

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
boolean_t didGetStates = [defaults boolForKey:@"didGetStates"];

if (didGetStates) {

    NSDictionary *dic = [tableData objectAtIndex:indexPath.row];

    int selectedState = [[dic valueForKey:@"State"] intValue];
    [cell.contentView addSubview:segmentedControl];

    if (selectedState == -1) {
        segmentedControl.selectedSegmentIndex = -1;
    }
    else {
        segmentedControl.selectedSegmentIndex = selectedState;
    }

    int comment = [[dic valueForKey:@"Comment"] intValue];
    int imageRef = [[dic valueForKey:@"Foto"] intValue];
    if (comment == 0) {
        [cell.contentView addSubview:commentView];
    }
    else {
        [[cell.contentView viewWithTag:98]removeFromSuperview];
    }
    if (imageRef == 0) {
        [cell.contentView addSubview:imageRefView];
    }
    else {
        [[cell.contentView viewWithTag:99]removeFromSuperview];
    }
}
MBFancyObject *object = _objects[indexPath.row];
cell.textLabel.text = object.title;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
object.selectedIndex = segmentedControl.selectedSegmentIndex;
object.currentIndexRow = indexPath.row;
cell.backgroundColor = [UIColor clearColor];
cell.textLabel.textColor = [UIColor whiteColor];

return cell;
}

选择细分时调用的操作。

- (IBAction)didChangeSegmentedControl:(UISegmentedControl *)sender {
// transform the origin of the cell to the frame of the tableView
CGPoint senderOriginInTableView = [self.tableView convertPoint:CGPointZero fromView:sender];

NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:senderOriginInTableView];
NSAssert(indexPath, @"must have a valid indexPath");
MBFancyObject *object = _objects[indexPath.row];
object.selectedIndex = sender.selectedSegmentIndex;
}

如果您有任何想法请写答案，或者如果您需要更多信息告诉我！ ：） 谢谢！！！

Mikkel-15岁的iDeveloper！ ;）

Answer 1

您误解了表格视图单元格的工作方式。 它们不是用于保存状态信息，而是用于呈现状态信息并与用户进行交互。

当表格视图单元格在屏幕外滚动时，系统将其扔到回收队列中，并且该单元格中的任何字段设置都会丢失。

当用户与表视图中的控件进行交互时，应立即将更改的信息保存到模型（数据存储）中。 然后，当表格视图要求您在tableView：cellForRowAtIndexPath：方法中提供一个单元格时，您应该使用模型中的值创建并完全配置一个单元格。

Answer 2

我发现我忘记了从数据库中获取数据，女巫返回-1。 并且，如果我选择段2，然后向下滚动然后向上备份，它将显示数据库中的值:)通过添加布尔值以检查在所选段之前的位置，它是可以修复的:)现在看起来像这样：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"FancyCell"];
cell = nil;
if (!cell) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"FancyCell"];
    cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
    // add the segmentedControl when you create a new cell
    UIImage *correctImageGreen = [[UIImage imageNamed:@"green.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UIImage *correctImageGul = [[UIImage imageNamed:@"gul.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UIImage *correctImageRed = [[UIImage imageNamed:@"red.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    NSArray *itemArray = [NSArray arrayWithObjects: correctImageGreen, correctImageGul, correctImageRed, nil];
    UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:itemArray];
    segmentedControl.frame = CGRectMake(308, 8, 150, 28);
    [cell.contentView addSubview:segmentedControl];

    // add an action so we can change our model if the view changes
    [segmentedControl addTarget:self action:@selector(didChangeSegmentedControl:) forControlEvents:UIControlEventValueChanged];

    // use a tag so we can retrieve the segmentedControl later
    segmentedControl.tag = 42;
}
// either if the cell could be dequeued or you created a new cell,
// segmentedControl will contain a valid instance
UISegmentedControl *segmentedControl = (UISegmentedControl *)[cell.contentView viewWithTag:42];

UIImage *comment = [UIImage imageNamed:@"Checkmark-hvid"];
UIImage *imageRef = [UIImage imageNamed:@"Checkmark-hvid"];
UIImageView *commentView = [[UIImageView alloc] initWithImage: comment];
UIImageView *imageRefView = [[UIImageView alloc] initWithImage: imageRef];
commentView.frame = CGRectMake(625, 5, 30, 30);
imageRefView.frame = CGRectMake(515, 5, 30, 30);
commentView.tag = 98;
imageRefView.tag = 99;

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
boolean_t didGetStates = [defaults boolForKey:@"didGetStates"];
boolean_t didSelectState = [defaults boolForKey:@"didSelectState"];

MBFancyObject *object = _objects[indexPath.row];

if (didGetStates) {
    NSDictionary *dic = [tableData objectAtIndex:indexPath.row];
    if (didSelectState) {
        segmentedControl.selectedSegmentIndex = object.selectedIndex;
    }
    else {
        int selectedState = [[dic valueForKey:@"State"] intValue];
        [cell.contentView addSubview:segmentedControl];

        if (selectedState == -1) {
            segmentedControl.selectedSegmentIndex = -1;
        }
        else {
            segmentedControl.selectedSegmentIndex = selectedState;
        }
    }

    int comment = [[dic valueForKey:@"Comment"] intValue];
    int imageRef = [[dic valueForKey:@"Foto"] intValue];
    if (comment == 0) {
        [cell.contentView addSubview:commentView];
    }
    else {
        [[cell.contentView viewWithTag:98]removeFromSuperview];
    }
    if (imageRef == 0) {
        [cell.contentView addSubview:imageRefView];
    }
    else {
        [[cell.contentView viewWithTag:99]removeFromSuperview];
    }

}
cell.textLabel.text = object.title;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
object.selectedIndex = segmentedControl.selectedSegmentIndex;
object.currentIndexRow = indexPath.row;
cell.backgroundColor = [UIColor clearColor];
cell.textLabel.textColor = [UIColor whiteColor];

return cell;
}

和segmentedControl的动作：

- (IBAction)didChangeSegmentedControl:(UISegmentedControl *)sender {
// transform the origin of the cell to the frame of the tableView
CGPoint senderOriginInTableView = [self.tableView convertPoint:CGPointZero fromView:sender];

NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:senderOriginInTableView];
NSAssert(indexPath, @"must have a valid indexPath");
MBFancyObject *object = _objects[indexPath.row];
object.selectedIndex = sender.selectedSegmentIndex;

[[NSUserDefaults standardUserDefaults] setBool:TRUE forKey:@"didSelectState"];
}