objective-c - UITableView 单元格中的 UITextField 返回 null

Question

在这个问题上我已经用头撞墙好一段时间了。非常感谢任何意见或方向。

所以我们的目标是从表格中的文本字段创建一个登录表单。该用户信息一旦被收集，将被传递到单独 View Controller 中的数组，因此可以存储在“收藏夹”列表中。

所以我创建了一个看起来很棒的表单，但是当我控制台输出表单结果时，字段返回(null)。我已经选择了该网站作为答案，但无法提供任何确切信息。下面是 cellForRowAtIndexPath: 方法我觉得问题可能出在我创建 textFields 的地方。再次感谢任何意见!

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
        static NSString *CellIdentifier = @"Cell";
        NSArray *listData =[self.tableContents objectForKey:[self.sortedKeys objectAtIndex:[indexPath section]]];

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

        if (cell == nil) {
                cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue2 
                                                                                                                                            reuseIdentifier:CellIdentifier] autorelease];

                textField = [[UITextField alloc] initWithFrame:CGRectMake(120, 13, 375, 30)];
                [textField retain];
        }

        textField.adjustsFontSizeToFitWidth = NO;
        textField.font = [UIFont fontWithName:@"Helvetica" size:14.0];
        textField.textColor = [UIColor darkGrayColor];
        textField.returnKeyType = UIReturnKeyDone;
        textField.backgroundColor = [UIColor clearColor];
        textField.autocorrectionType = UITextAutocorrectionTypeNo; 
        textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
        textField.textAlignment = UITextAlignmentLeft;
        textField.clearButtonMode = UITextFieldViewModeNever;
        textField.delegate = self;

        if ([indexPath section] == 0) {
                switch (indexPath.row) {
                        case 0:
                                textField.placeholder = @"Optional";
                                textField.secureTextEntry = NO;
                                textField.keyboardType = UIKeyboardTypeDefault;
                                textField.tag = 0;
                                break;
                        case 1:
                                textField.placeholder = @"";
                                textField.secureTextEntry = NO;
                                textField.keyboardType = UIKeyboardTypeDefault;
                                textField.tag = 1;
                                break;
                        case 2:
                                textField.placeholder = @"";
                                textField.secureTextEntry = NO;
                                textField.keyboardType = UIKeyboardTypeDefault;
                                textField.tag = 2;
                                break;
                        case 3:
                                textField.placeholder = @"";
                                textField.secureTextEntry = YES;
                                textField.keyboardType = UIKeyboardTypeDefault;
                                textField.tag = 3;
                                break;
                        case 4:
                                textField.placeholder = @"Optional";
                                textField.secureTextEntry = NO;
                                textField.keyboardType = UIKeyboardTypeDefault;
                                textField.tag = 4;
                                break;
                        case 5:
                                textField.placeholder = @"Optional";
                                textField.secureTextEntry = NO;
                                textField.keyboardType = UIKeyboardTypeNumberPad;
                                textField.tag = 5;
                                break;
                }               
        }

        [textField setEnabled: YES];

        [cell addSubview:textField];

  cell.textLabel.text = [listData objectAtIndex:indexPath.row];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        cell.accessoryType = UITableViewCellAccessoryNone;
        cell.editing = YES;

        return cell;
}

Answer 1

textField 变量(我假设它是类中的 ivar 或静态全局变量)是您的主要问题。每次创建新单元格时都会创建一个新的文本字段，这很好，但是每次调用 cellForRowAtIndexPath 方法时都会将它添加到单元格中。由于细胞被重复使用，这会把事情搞砸。

您的代码需要如下所示:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";
    NSArray *listData =[self.tableContents objectForKey:[self.sortedKeys objectAtIndex:[indexPath section]]];

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue2                                                                                                   reuseIdentifier:CellIdentifier] autorelease];

            cell.selectionStyle = UITableViewCellSelectionStyleNone;
            cell.accessoryType = UITableViewCellAccessoryNone;
            cell.editing = YES;

            UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(120, 13, 375, 30)];
            textfield.tag = 1;
            textField.adjustsFontSizeToFitWidth = NO;
            textField.font = [UIFont fontWithName:@"Helvetica" size:14.0];
            textField.textColor = [UIColor darkGrayColor];
            textField.returnKeyType = UIReturnKeyDone;
            textField.backgroundColor = [UIColor clearColor];
            textField.autocorrectionType = UITextAutocorrectionTypeNo; 
            textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
            textField.textAlignment = UITextAlignmentLeft;
            textField.clearButtonMode = UITextFieldViewModeNever;
            textField.delegate = self;
            [textField setEnabled: YES];

            [cell.contentView addSubview:textField];
            [textField release];
    }

    UITextField *textField = (UITextField *) [cell.contentView viewWithTag:1];

    if ([indexPath section] == 0) {
            switch (indexPath.row) {
                    case 0:
                            textField.placeholder = @"Optional";
                            textField.secureTextEntry = NO;
                            textField.keyboardType = UIKeyboardTypeDefault;
                            break;
                    case 1:
                            textField.placeholder = @"";
                            textField.secureTextEntry = NO;
                            textField.keyboardType = UIKeyboardTypeDefault;
                            break;
                    case 2:
                            textField.placeholder = @"";
                            textField.secureTextEntry = NO;
                            textField.keyboardType = UIKeyboardTypeDefault;
                            break;
                    case 3:
                            textField.placeholder = @"";
                            textField.secureTextEntry = YES;
                            textField.keyboardType = UIKeyboardTypeDefault;
                            break;
                    case 4:
                            textField.placeholder = @"Optional";
                            textField.secureTextEntry = NO;
                            textField.keyboardType = UIKeyboardTypeDefault;
                            break;
                    case 5:
                            textField.placeholder = @"Optional";
                            textField.secureTextEntry = NO;
                            textField.keyboardType = UIKeyboardTypeNumberPad;
                            break;
            }               
    }

    textField.text = [listData objectAtIndex:indexPath.row];

    return cell;
}

不确定这是否完全符合您的要求，但它应该能为您指明正确的方向。