滚动单元格双端队列时如何维护和保存自定义单元格文本字段条目数据

Posted 2023-02-27

【中文标题】滚动单元格双端队列时如何维护和保存自定义单元格文本字段条目数据

【英文标题】：How do I maintain and save custom cell textfield entry data when scrolling cells deque

【发布时间】：2013-06-02 18:35:07

【问题描述】：

遗憾的是，我知道问题出在哪里，但我是新手，不知道处理它的最佳方法。我已阅读此处的苹果文档和所有相关问题，但无法充分找到或解释这些信息。

如下所示。我有一个包含 19 个单元格的表格视图。第 0 节中的 2，第 1 节中的 17。除了滚动时，一切正常，我知道这是因为 tableview 正在重用单元格，所以当我尝试保存时，如下面的代码中所示，这些单元格根本不存在因此，当我尝试保存时，我认为不存在的任何内容都是 nil 字符串参数，因此我的实体最终为 NaN。

从我的所有单元格中维护和保存文本字段信息的适当方法是什么？提前感谢您的帮助！

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

    UITableViewCell *newCell;

if (indexPath.section == 0 && indexPath.row == 0) 
    NSString *cellIdentifier = @"RNDateCell";
    RNCommentCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (cell == nil) 
        NSArray *nib = [[NSBundle mainBundle]loadNibNamed:@"RNCommentCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
        cell.commentLabel.text = NSLocalizedString(@"Date:", @"Date:");
        cell.commentField.text = [NSString stringWithFormat:@"%@", self.metrics.timeStamp.description];
        newCell = cell;
    


if (indexPath.section == 0 && indexPath.row == 1) 
    NSString *cellIdentifier = @"RNCommentCell";
    RNCommentCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (cell == nil) 
        NSArray *nib = [[NSBundle mainBundle]loadNibNamed:@"RNCommentCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
        cell.commentLabel.text = NSLocalizedString(@"Comment:", @"Comment:");
        cell.commentField.text = self.metrics.comment;
        newCell = cell;
    


if (indexPath.section == 1) 
    static NSString *numericCellIdentifier = @"RNNumericCell";
    RNNumericCell *cell = (RNNumericCell *)[tableView dequeueReusableCellWithIdentifier:numericCellIdentifier];
    if (cell == nil) 
        NSArray *nib = [[NSBundle mainBundle]loadNibNamed:@"RNNumericCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];

        switch (indexPath.row) 
            case 0:
                cell.numericCellLabel.text = NSLocalizedString(@"Weight:", @"Weight:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.weight];
                newCell = cell;
                break;
            case 1:
                cell.numericCellLabel.text = NSLocalizedString(@"Height:", @"Height:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.height];
                newCell = cell;
                break;
            case 2:
                cell.numericCellLabel.text = NSLocalizedString(@"Neck:", @"Neck:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.neck];
                newCell = cell;
                break;
            case 3:
                cell.numericCellLabel.text = NSLocalizedString(@"Chest:", @"Chest:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.chest];
                newCell = cell;
                break;
            case 4:
                cell.numericCellLabel.text = NSLocalizedString(@"Waist:", @"Waist:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.waist];
                newCell = cell;
                break;
            case 5:
                cell.numericCellLabel.text = NSLocalizedString(@"Hips:", @"Hips:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.hips];
                newCell = cell;
                break;
            case 6:
                cell.numericCellLabel.text = NSLocalizedString(@"Biceps:", @"Biceps:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.biceps];
                newCell = cell;
                break;
            case 7:
                cell.numericCellLabel.text = NSLocalizedString(@"Forearms:", @"Forearms:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.forearms];
                newCell = cell;
                break;
            case 8:
                cell.numericCellLabel.text = NSLocalizedString(@"Wrists:", @"Wrists:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.wrists];
                newCell = cell;
                break;
            case 9:
                cell.numericCellLabel.text = NSLocalizedString(@"Quads Thighs:", @"Quads Thighs:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.quadsThighs];
                newCell = cell;
                break;
            case 10:
                cell.numericCellLabel.text = NSLocalizedString(@"Calves:", @"Calves:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.calves];
                newCell = cell;
                break;
            case 11:
                cell.numericCellLabel.text = NSLocalizedString(@"Ankles:", @"Ankles:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.ankles];
                newCell = cell;
                break;
            case 12:
                cell.numericCellLabel.text = NSLocalizedString(@"Feet:", @"Feet:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.feet];
                newCell = cell;
                break;
            case 13:
                cell.numericCellLabel.text = NSLocalizedString(@"BMI:", @"BMI:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.bmi];
                newCell = cell;
                break;
            case 14:
                cell.numericCellLabel.text = NSLocalizedString(@"BMR:", @"BMR:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.bmr];
                newCell = cell;
                break;
            case 15:
                cell.numericCellLabel.text = NSLocalizedString(@"Waist/Height R:", @"Waist/Height R:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.waistToHeightRatio];
                newCell = cell;
                break;
            case 16:
                cell.numericCellLabel.text = NSLocalizedString(@"Waist/Hips R:", @"Waist/Hips R:");
                cell.numericField.text = [NSString stringWithFormat:@"%@", self.metrics.waistToHipRatio];
                newCell = cell;
                break;
            default:
                break;
        
    

return newCell;

    - (void)saveData

NSDateFormatter *dateFormat;
RNCommentCell *dateCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];
self.metrics.timeStamp = [dateFormat dateFromString:dateCell.commentField.text];

RNCommentCell *commentCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:0]];
self.metrics.comment = commentCell.commentField.text;


RNNumericCell *weightCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:1]];
self.metrics.weight = [NSDecimalNumber decimalNumberWithString:weightCell.numericField.text];

RNNumericCell *heightCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:1 inSection:1]];
self.metrics.height = [NSDecimalNumber decimalNumberWithString:heightCell.numericField.text];

RNNumericCell *neckCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:2 inSection:1]];
self.metrics.neck = [NSDecimalNumber decimalNumberWithString:neckCell.numericField.text];

RNNumericCell *chestCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:3 inSection:1]];
self.metrics.chest = [NSDecimalNumber decimalNumberWithString:chestCell.numericField.text];

RNNumericCell *waistCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:4 inSection:1]];
self.metrics.waist = [NSDecimalNumber decimalNumberWithString:waistCell.numericField.text];

RNNumericCell *hipsCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:5 inSection:1]];
self.metrics.hips = [NSDecimalNumber decimalNumberWithString:hipsCell.numericField.text];

RNNumericCell *bicepsCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:6 inSection:1]];
self.metrics.biceps = [NSDecimalNumber decimalNumberWithString:bicepsCell.numericField.text];

RNNumericCell *forearmCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:7 inSection:1]];
self.metrics.forearms = [NSDecimalNumber decimalNumberWithString:forearmCell.numericField.text];

RNNumericCell *wristsCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:8 inSection:1]];
self.metrics.wrists = [NSDecimalNumber decimalNumberWithString:wristsCell.numericField.text];

RNNumericCell *quadsCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:9 inSection:1]];
self.metrics.quadsThighs = [NSDecimalNumber decimalNumberWithString:quadsCell.numericField.text];

RNNumericCell *calvesCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:10 inSection:1]];
self.metrics.calves = [NSDecimalNumber decimalNumberWithString:calvesCell.numericField.text];

RNNumericCell *anklesCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:11 inSection:1]];
self.metrics.ankles = [NSDecimalNumber decimalNumberWithString:anklesCell.numericField.text];

RNNumericCell *feetCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:12 inSection:1]];
self.metrics.feet = [NSDecimalNumber decimalNumberWithString:feetCell.numericField.text];

RNNumericCell *bmiCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:13 inSection:1]];
self.metrics.bmi = [NSDecimalNumber decimalNumberWithString:bmiCell.numericField.text];

RNNumericCell *bmrCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:14 inSection:1]];
self.metrics.bmr = [NSDecimalNumber decimalNumberWithString:bmrCell.numericField.text];

RNNumericCell *waistToHeightCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:15 inSection:1]];
self.metrics.waistToHeightRatio = [NSDecimalNumber decimalNumberWithString:waistToHeightCell.numericField.text];

RNNumericCell *waistToHipCell = (id)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:16 inSection:1]];
self.metrics.waistToHipRatio = [NSDecimalNumber decimalNumberWithString:waistToHipCell.numericField.text];

NSError *error;
if (![self.managedObjectContext save:&error]) 
    NSLog(@"Error saving context: %@", error);

【参考方案1】：

请记住，UITextField 是视图，不应存储数据而只是显示/检索数据。您的模型 (self.metrics) 应该是您存储信息的位置，并且应该在您从用户那里收到信息后立即存储它，这样文本字段是否消失或被重复使用都无关紧要。

为了做到这一点，您可以使用以下方法，当有人停止编辑文本字段时调用该方法（确保将所有文本字段的委托设置为您的控制器）：

-(void) textFieldDidEndEditing:(UITextField *)textField

    // Figure out which textField this is and save the data to the appropriate place in your model

现在，有点棘手的部分是确定您在此方法中使用的文本字段。

您可以在 cellForRowAtIndexPath 中设置标签，然后在此处查找标签号以确定它是什么，或者您可以通过索引路径进行，因为无论如何您已经在做：

CGRect position = [self convertRect:textField.frame toView:self.tableView];
NSArray *indexPaths = [self.tableView indexPathsForRowsInRect:position];
NSIndexPath *indexPath = [indexPaths objectAtIndex:0];

【讨论】：

非常感谢这帮助我了解了实现它的正确方法。我不够聪明，无法弄清楚如何使用您提供的索引代码。然而，只需为我的单元格中的每一行添加 cell.texfield.tag = XXXX 作为索引路径，然后在 texfielddidendediting 中引用所述单元格以将数据保存到我的模型中，这对我来说很容易遵循并且效果很好，希望这是一种经过批准且足够有效的方法。干杯，再次感谢！

不客气！您使用 indexPath 的方式与在 cellForRowAtIndexPath 中使用的方式相同。无论哪种方式都是一种完全有效的方式！由于您是该网站的新手，请务必通过单击旁边的向上箭头对所有对您有帮助的答案（无论您是否提出问题）投票。 :)

非常感谢，现在我有声望了！

【参考方案2】：

在您的self.metrics.'whatever' 数据发生更改时更新它，并且只将指标保存在您的save 中，而不是尝试从单元格中获取它。换句话说，不要将单元格用作数据存储位置。

【讨论】：

谢谢你，这有助于我更好地看待事情。现在只是实现它。