dequeueReusableCellWithIdentifier:对于可见单元格始终返回"nil" [英] dequeueReusableCellWithIdentifier: always returns 'nil' for visible cells

问题描述

我创建了一个自定义表格视图单元格.

I create a custom table view cell.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITextField *editField=nil;
...

NSString *CellIdentifier = [NSString  stringWithFormat:@"cell:%d",indexPath.row];

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];

    // Configure the cell...
    switch (indexPath.row) {

        case 0: 
        {

            cell.textLabel.text=DEVNAME_TEXT_NDVC;
            cell.textLabel.font=[UIFont boldSystemFontOfSize:LABEL_TEXTSIZE_NDVC];

            editField=[[UITextField alloc] initWithFrame:CGRectMake(158, 9, cell.frame.size.width-183, cell.frame.size.height-15) ];
            editField.tag=DEVNAME_TAG_NDVC;
            ...
            [cell.contentView addSubview:editField ];
            [editField release];

        }
        break;

该表只有5行，并且每行始终在屏幕上. 后来，当我尝试访问该单元格时，我总是得到"nil"

The table has 5 lines only, and each of them is on the screen always. Later, when I try to get access to the cell I always get 'nil'

下面的代码应在用户点击单元格时将光标放置在适当的UITextField上，但不会，因为'cell'始终为= 0.

The following code should place cursor to apropriate UITextField when user tap the cell, but it doesn't, since 'cell' is always =0.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { 
NSString *CellIdentifier = [NSString stringWithFormat:@"cell:%d",indexPath.row];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
UITextField *tf=nil;

[tableView deselectRowAtIndexPath: indexPath animated: YES];
[activeField resignFirstResponder]; // Last used UITextField

switch (indexPath.row) {
    case 0: //
        tf=(UITextField*)[cell.contentView viewWithTag:DEVNAME_TAG_NDVC];
        [tf becomeFirstResponder]; // Show the keyboard
        //[tf performSelector:@selector(becomeFirstResponder) withObject:nil afterDelay:0.7];
    break;

请，您能建议出什么问题吗?为什么[tableView dequeueReusableCellWithIdentifier:CellIdentifier]总是= 0， 但是所有表格单元格始终可见.

Please, could you suggest what is wrong? Why [tableView dequeueReusableCellWithIdentifier:CellIdentifier] always =0, but all of the table cells are always visible.

谢谢.

推荐答案

也许我听不懂这个问题，但是表格单元格仅在不再显示时才变得可重用吗?如果它们仍然可见，您如何重用它们?

Maybe I don't understand the question, but don't table cells only become reusable once they are no longer being displayed? If they are still visible, how could you reuse them?

这篇关于dequeueReusableCellWithIdentifier:对于可见单元格始终返回"nil"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！