tableView 滚动时添加了重复的 UITextField答案

【问题标题】：Duplicate UITextField's being added when tableView scrollstableView 滚动时添加了重复的 UITextField
【发布时间】：2014-02-11 14:59:20
【问题描述】：

我遇到了一个问题，即重复使用单元格时添加了重复的 UITextField，这不是我想要发生的。我记得以前遇到过类似的问题，但是对于我的生活，我不记得我做了什么来解决它。

毫无疑问，这很明显，但我似乎找不到任何有用的东西。正如某些人所建议的那样，我已经尝试将 if/else 语句包含在“if (cell == null)”中，但这只会导致形成一个空白表。

我们将不胜感激一些建议。

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];


        if (indexPath.section == 0){

            productField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
            [productField setPlaceholder:@"Product"];
            if ([productData length] > 0){
                [productField setText:productData];
                [productField setEnabled:false];
            }
            [cell addSubview:productField];

        } else if (indexPath.section == 1){

            issueField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
            [issueField setPlaceholder:@"What's the issue?"];
            [issueField setAutocorrectionType:UITextAutocorrectionTypeNo];
            [cell addSubview:issueField];

        } else if (indexPath.section == 2){

            emailField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
            [emailField setPlaceholder:@"Email address"];
            [emailField setAutocorrectionType:UITextAutocorrectionTypeNo];
            [emailField setAutocapitalizationType:UITextAutocapitalizationTypeNone];
            [emailField setKeyboardType:UIKeyboardTypeEmailAddress];
            [cell addSubview:emailField];

        } else if (indexPath.section == 3){

            notesField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
            [notesField setPlaceholder:@"Any notes to add?"];
            [notesField setAutocorrectionType:UITextAutocorrectionTypeNo];
            [cell addSubview:notesField];

        } else if (indexPath.section == 4){

            sendFeedback = [[UIButton alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
            [sendFeedback setTitle:@"Send Feedback" forState:UIControlStateNormal];
            [sendFeedback setBackgroundColor:[UIColor colorWithRed:(111/255.0f) green:(31/255.0f) blue:(68/255.0f) alpha:1.0f]];
            [sendFeedback.titleLabel setFont:[UIFont fontWithName:@"MaryAnn" size:20.0]];
            [sendFeedback addTarget:self action:@selector(sendFeedback:) forControlEvents:UIControlEventTouchUpInside];
            [cell setBackgroundColor:[UIColor clearColor]];
            [cell addSubview:sendFeedback];

        }


    return cell;
}

【问题讨论】：

你应该使用静态单元格代替 dequeueReusableCell 它们。
你不能创建自定义单元格吗？
感谢您的帮助。我选择了静态单元格（完全忘记了它们），因为它只会在测试版本中使用，而不是在应用程序的生产版本中使用。

标签： ios objective-c uitableview uitextfield

【解决方案1】：

你的问题是表格视图中的可重用单元格，试试这个代码

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if(cell == nil)
    {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
        cell.selectionStyle=UITableViewCellSelectionStyleNone;
        UITextField* textField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        textField.tag=101;
        [cell addSubview:textField];

        UIButton *sendFeedback = [[UIButton alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        sendFeedback.tag=102;
        [sendFeedback setTitle:@"Send Feedback" forState:UIControlStateNormal];
        [sendFeedback setBackgroundColor:[UIColor colorWithRed:(111/255.0f) green:(31/255.0f) blue:(68/255.0f) alpha:1.0f]];
        [sendFeedback.titleLabel setFont:[UIFont fontWithName:@"MaryAnn" size:20.0]];
        [sendFeedback addTarget:self action:@selector(sendFeedback:) forControlEvents:UIControlEventTouchUpInside];
        [cell setBackgroundColor:[UIColor clearColor]];
        [cell addSubview:sendFeedback];

    }
    UITextField* textField=(UITextField*)[cell viewWithTag:101];
    UIButton *sendFeedback = (UIButton*)[cell viewWithTag:102];
    sendFeedback.hidden=YES;
    textField.hidden=NO;
     [textField setKeyboardType:UIKeyboardTypeDefault];
    if (indexPath.section == 0)
    {
        [textField setPlaceholder:@"Product"];
        if ([productData length] > 0)
        {
            [textField setText:productData];
            [textField setEnabled:false];
        }

    } else if (indexPath.section == 1){

        [textField setPlaceholder:@"What's the issue?"];
        [textField setAutocorrectionType:UITextAutocorrectionTypeNo];

    } else if (indexPath.section == 2){

        [textField setPlaceholder:@"Email address"];
        [textField setAutocorrectionType:UITextAutocorrectionTypeNo];
        [textField setAutocapitalizationType:UITextAutocapitalizationTypeNone];
        [textField setKeyboardType:UIKeyboardTypeEmailAddress];

    } else if (indexPath.section == 3){

        [textField setPlaceholder:@"Any notes to add?"];
        [textField setAutocorrectionType:UITextAutocorrectionTypeNo];

    } else if (indexPath.section == 4)
    {
        textField.hidden=YES;
        sendFeedback.hidden=NO;
    }

    return cell;
}

// 在表格视图中不能直接访问 textField.text，而是使用全局变量或字典来分配 textField.text

【讨论】：

【解决方案2】：

这是因为您不断将子视图添加到单元格中。例如，您将 productField 添加到索引 0 处的单元格。当该单元格被重用时，您向其添加另一个子视图，但 productField 仍然存在。一种可能的解决方案是在添加新子视图之前删除子视图。你的if 声明会是这样的：

    if (indexPath.section == 0){
        // Remove the old subview
        UIView *oldSubview = [cell viewWithTag:5];
        [oldSubview removeFromSuperview];

        productField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [productField setPlaceholder:@"Product"];
        if ([productData length] > 0){
            [productField setText:productData];
            [productField setEnabled:false];
        }
        // Set a tag for the new subview, so you can remove it later
        productField.tag = 5;
        [cell addSubview:productField];
    }

在每个if 语句中使用相同的tag。

编辑：

或者你也可以像@pawan 建议的那样使用静态单元格。

【讨论】：

【解决方案3】：

问题在于，由于您正在回收单元格（并且应该），因此您正在重用非空单元格并在其上添加新控件。

通常的处理方法是构建您的自定义 UITableViewCell 子类，并将各种文本字段和其他 UI 控件作为属性。然后您可以在每个部分中显示/隐藏这些 UI 控件

看起来像这样：

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
        if (indexPath.section == 0){
            productField.hidden=NO;
            issueField.hidden=YES;

        } else if (indexPath.section == 1){
            productField.hidden=YES;
            issueField.hidden=NO;
        }
return cell;
}

【讨论】：

【解决方案4】：

为什么不实例化单元格后，从单元格内容视图中删除所有子视图

for( UIView *view in cell.contentView.subviews )
    [view removeFromSuperview];

【讨论】：

【解决方案5】：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *CellIdentifier = [NSString stringWithFormat:@"Cell %d",indexPath.section];

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    cell = nil;
    if (cell == nil)
    {

    if (indexPath.section == 0)
    {

        productField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [productField setPlaceholder:@"Product"];
        if ([productData length] > 0){
            [productField setText:productData];
            [productField setEnabled:false];
        }
        [cell addSubview:productField];

    }
    else if (indexPath.section == 1)
    {

        issueField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [issueField setPlaceholder:@"What's the issue?"];
        [issueField setAutocorrectionType:UITextAutocorrectionTypeNo];
        [cell addSubview:issueField];

    } else if (indexPath.section == 2){

        emailField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [emailField setPlaceholder:@"Email address"];
        [emailField setAutocorrectionType:UITextAutocorrectionTypeNo];
        [emailField setAutocapitalizationType:UITextAutocapitalizationTypeNone];
        [emailField setKeyboardType:UIKeyboardTypeEmailAddress];
        [cell addSubview:emailField];

    } else if (indexPath.section == 3){

        notesField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [notesField setPlaceholder:@"Any notes to add?"];
        [notesField setAutocorrectionType:UITextAutocorrectionTypeNo];
        [cell addSubview:notesField];

    } else if (indexPath.section == 4){

        sendFeedback = [[UIButton alloc] initWithFrame:CGRectMake(10, 0, 300, 45)];
        [sendFeedback setTitle:@"Send Feedback" forState:UIControlStateNormal];
        [sendFeedback setBackgroundColor:[UIColor colorWithRed:(111/255.0f) green:(31/255.0f) blue:(68/255.0f) alpha:1.0f]];
        [sendFeedback.titleLabel setFont:[UIFont fontWithName:@"MaryAnn" size:20.0]];
        [sendFeedback addTarget:self action:@selector(sendFeedback:) forControlEvents:UIControlEventTouchUpInside];
        [cell setBackgroundColor:[UIColor clearColor]];
        [cell addSubview:sendFeedback];

    }

    }
    return cell;
}

【讨论】：