TextField第一个单元格结果显示在Tableview单元格的其他单元格中

Question

我正在开发IOS应用程序。 问题是在表视图中使用文本字段。 在tableviewCell的文本字段第一个单元格中输入的值，结果显示在第二个或第三个单元格中。 有时，当表视图只有一行时，结果会正确显示。 任何帮助或建议，我们将不胜感激。

码：

(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

   return _fetchedobj.count;
}

(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
   static NSString *MyIdentifier = @"MyReuseIdentifier";
   UITableViewCell *cell = [myTable dequeueReusableCellWithIdentifier:MyIdentifier];
   if (cell == nil) {
      cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault  reuseIdentifier:MyIdentifier];
   }
   data = [_fetchedobj objectAtIndex:indexPath.row];

   _quantity = [[UITextField alloc] initWithFrame:CGRectMake(5.0f,28.0f,50.0f , 30.0f)];
   [_quantity setFont:[UIFont systemFontOfSize:14.0f]];
   [_quantity setTextAlignment:NSTextAlignmentCenter];
   _quantity.backgroundColor = [UIColor whiteColor];
   [_quantity setAdjustsFontSizeToFitWidth:YES];
   [_quantity addTarget:self action:@selector(changedvalue:) forControlEvents:UIControlEventAllEditingEvents];
   NSString *q_value = [data valueForKey:@"quantity"];
   NSInteger q_value1 = [q_value integerValue];
   [_quantity setText:[NSString stringWithFormat:@"%ld",(long)q_value1]];
   [cell addSubview:_quantity];

变更价值方法

- (void) changedvalue: (UITextField *)textfield
{

    NSString *text = [textfield text];
    NSInteger text1 = [text integerValue];

    NSString *changevalue =  [dict objectForKey:@"_max_purchases_per_user"];
    NSInteger valueChange =  [changevalue integerValue];
    NSString *userPurchase = [dict objectForKey:@"_max_purchases"];
    NSInteger itemPurchase = [userPurchase integerValue];

    NSString *amount =  [data valueForKey:@"amount"];
    NSInteger amount1 = [amount integerValue];

    NSInteger minValue=MIN(valueChange, itemPurchase);
    if (text1 > minValue) {
        [_quantity setText:[NSString stringWithFormat:@"%ld",(long)minValue]];
        [_total1 setText:[NSString stringWithFormat:@"%ld",minValue * amount1]];
    }else{
   [_total1 setText:[NSString stringWithFormat:@"%ld",text1 * amount1]];
    }
  integerValue] * [aNum integerValue])]];
}

Answer 1

您需要了解单元重用的概念。 您可以采取一些措施来解决此问题。

首先是您的cellForRowAtIndexPath:方法。 每次调用该方法时，即使可能已经存在一个新的UITextField，也要放置一个。 另外， _quantity似乎是_quantity的实例变量，这不是一个好习惯。

(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

   return _fetchedobj.count;
}

(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
   static NSString *MyIdentifier = @"MyReuseIdentifier";
   UITableViewCell *cell = [myTable dequeueReusableCellWithIdentifier:MyIdentifier];

   UITextField *quantity;

   if (cell == nil) {
      cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault  reuseIdentifier:MyIdentifier];

      //This is the only place a new UITextField is needed.


       quantity = [[UITextField alloc] initWithFrame:CGRectMake(5.0f,28.0f,50.0f , 30.0f)];
       [quantity setFont:[UIFont systemFontOfSize:14.0f]];
       [quantity setTextAlignment:NSTextAlignmentCenter];
       quantity.backgroundColor = [UIColor whiteColor];
       [quantity setAdjustsFontSizeToFitWidth:YES];
       [quantity addTarget:self action:@selector(changedvalue:) forControlEvents:UIControlEventAllEditingEvents];
       [quantity setTag: 1];
       [cell addSubview:quantity];

   }
   else
   {
       quantity = [cell viewWithTag: 1];
   }

   data = [_fetchedobj objectAtIndex:indexPath.row];
   NSString *q_value = [data valueForKey:@"quantity"];
   NSInteger q_value1 = [q_value integerValue];
   [quantity setText:[NSString stringWithFormat:@"%ld",(long)q_value1]];
}

其次，在changedValue:方法中，您没有将要更新的值存储在cellForRowAtIndexPath：方法中要更新的任何位置。 另外，您需要一种跟踪textField属于哪个单元格的方法。

- (void) changedvalue: (UITextField *)textfield
{
    NSIndexPath *indexPath = [self.tableView indexPathForCell: textfield.superview ];    

    NSString *text = [textfield text];
    NSInteger text1 = [text integerValue];

    NSString *changevalue =  [dict objectForKey:@"_max_purchases_per_user"];
    NSInteger valueChange =  [changevalue integerValue];
    NSString *userPurchase = [dict objectForKey:@"_max_purchases"];
    NSInteger itemPurchase = [userPurchase integerValue];

    NSString *amount =  [data valueForKey:@"amount"];
    NSInteger amount1 = [amount integerValue];

    NSInteger minValue=MIN(valueChange, itemPurchase);
    if (text1 > minValue) {
        [textField setText:[NSString stringWithFormat:@"%ld",(long)minValue]];
        [_total1 setText:[NSString stringWithFormat:@"%ld",minValue * amount1]];
    }else{
        [_total1 setText:[NSString stringWithFormat:@"%ld",text1 * amount1]];
    }

  // integerValue] * [aNum integerValue])]]; This line is incomplete

   //Update the new value in the array.
   NSMutableArray *mData = [data mutableCopy];
   NSMutableDictionary *mdic = [data objectAtIndex: indexPath.row].mutableCopy;
   [mDic setObject:textField.text];
   [mData replaceObjectAtIndex:indexPath.row withObject:mDic];
   data = mData;
}

Answer 2

首先，从不建议您直接将子视图添加到单元格。 如果要自定义某些内容，请创建UITableViewCell的子类，然后将UITextField作为子视图添加到单元格的contentView而不是直接添加到该视图。

假设您的自定义单元格为MyCustomCell，其中包含textField。

然后您的cellForRowAtIndexPath：应该看起来像-

(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *MyIdentifier = @"MyReuseIdentifier";
    MyCustomCell *cell = [myTable dequeueReusableCellWithIdentifier:MyIdentifier];

    if (cell == nil) {
        cell = [[MyCustomCell alloc] initWithStyle:UITableViewCellStyleDefault  reuseIdentifier:MyIdentifier];
    }

    // All the rendering of quantity should be done in MyCustomCell and quantity should be added as subview to its contentView. And you should also implement prepareForReuse method in your custom cell.

    data = [_fetchedobj objectAtIndex:indexPath.row];
    NSString *q_value = [data valueForKey:@"quantity"];
    NSInteger q_value1 = [q_value integerValue];
    // here you should just assign the data to the cell and your view controller should know nothing about the rendering of cell.
    cell.quantity.text = [NSString stringWithFormat:@"%ld",(long)q_value1];
}

Answer 3

您应该在tableView:willDisplayCell:forRowAtIndexPath方法而不是cellForRowAtIndexPath方法中设置表视图单元格的内容，因为Cocoa会尝试为当前单元格使用最后创建的单元格（可能已缓存）。