iPhone-在表格视图滚动文本字段设置为零

Posted 2023-02-27

【中文标题】iPhone-在表格视图滚动文本字段设置为零

【英文标题】：iPhone- on table view scrolling text fields set to nil

【发布时间】：2011-10-28 21:16:59

【问题描述】：

我在表格视图中添加了几个单元格，每个单元格右侧都有一个 textField 让用户输入文本。我还为此添加了一个自定义单元类。我发现当我向下滚动并返回时，前几行的输入会消失。有谁知道问题出在哪里？

这是我的一段代码

@implementation MyCell
-(void)setData:(NSString*)str 


  UIImage *image = [UIImage imageNamed:@"cellImage copy.png"];
  [[self imageView ]setImage:image];

  lblLocations=[[UILabel alloc]init];
  lblLocations.textAlignment=UITextAlignmentLeft;
  lblLocations.backgroundColor = [UIColor clearColor];
  lblLocations.font = [UIFont boldSystemFontOfSize:12];
   lblLocations.numberOfLines = 2;
  lblLocations.lineBreakMode = UILineBreakModeWordWrap;
  lblLocations.textAlignment = UITextAlignmentCenter;
   lblLocations.text =str ;
  NSLog(@"the title is%@",str);
  [[self contentView]addSubview:lblLocations];
  [lblLocations release];

  txtUnits=[[UITextField alloc]init];
    [txtUnits setAdjustsFontSizeToFitWidth:YES];
  txtUnits.textAlignment = UITextAlignmentCenter;

  txtUnits.returnKeyType = UIReturnKeyDone;
  txtUnits.autocapitalizationType = NO;
  txtUnits.textColor = [UIColor blackColor];
  //following condition is not working when i'm scrolling up after writing into some of cell's text fields or i can say never working at all
  if ([textDict valueForKey:[NSString stringWithFormat:@"%d",rowNum]]) 
    [txtUnits setText:[textDict valueForKey:[NSString stringWithFormat:@"%d",rowNum]]];
  
  else
  
    [txtUnits setPlaceholder:@"0.00"];
  
  [txtUnits setValue:[UIColor blackColor] 
          forKeyPath:@"_placeholderLabel.textColor"];
  [[self contentView]addSubview:txtUnits];
  txtUnits.backgroundColor = [UIColor clearColor];
  txtUnits.delegate = self;
    [txtUnits release];

-(void)textFieldDidEndEditing:(UITextField *)textField

  [textDict setObject:textField.text forKey:[NSString stringWithFormat:@"%d",rowNum]]; 

and cellforrow....

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

  static NSString *CellIdentifier = @"Cell";


  UITableViewCell *cell=nil;
  if (cell == nil) 
      cell = [[[MyCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier androw:[indexPath row]] autorelease];
  
  cell.selectionStyle = UITableViewCellSelectionStyleNone;

  NSMutableDictionary *dict=(NSMutableDictionary*)[locations objectAtIndex:[indexPath section]];

  NSMutableArray *array=(NSMutableArray*)[dict objectForKey:@"locationsArray"];

  MyCell *modelObj=(MyCell*)[array objectAtIndex:indexPath.row];

  NSLog(@"the values of the array are%@",modelObj.title);
  NSString *str = modelObj.title;
  [(MyCell *)cell setData:str];
 return cell;

检查文本是否输入到特定单元格的文本字段中的逻辑应该是什么？请帮忙！

【参考方案1】：

嗯——为什么每次调用 cellForRowAtIndexPath 时都要重新分配一个 MyCell？在我看来，您应该更喜欢以下内容：

static NSString *CellIdentifier = @"Cell";

MyCell* cell = (MyCell*)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

if (!cell) 
...

另外，您还使用视图类作为模型类似乎很奇怪——辅助locations 字典是如何维护的？如果实际上模型实例与视图实例相同，为什么要重复？