title: IOS how to update UITableViewCell
body: <p>i make a custom UITableViewCell:</p>
  
  <pre><code> SListViewCell * cell = nil;
  //    cell = [listView dequeueReusableCellWithIdentifier:CELL];
  if (!cell) {
      cell = [[[SListViewCell alloc] initWithReuseIdentifier:CELL] autorelease];
  }
  listView.separatorColor = [UIColor clearColor];
  cell.backgroundColor = [UIColor clearColor];
  cell.selectionStyle = UITableViewCellSelectionStyleNone;
  UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom];
  btn.tag = index;
  [btn setFrame:CGRectMake(0, 0, 42, 42)];
  //setBtnImage will download image from network. when the UIButton click it is will change button image 
  [self setBtnImage:index btn:btn];
  [btn addTarget:self action:@selector(typeTapped:) forControlEvents:UIControlEventTouchUpInside];
  [cell addSubview:btn];
  return  cell;
  </code></pre>
  
  <p>typeTapped method:</p>
  
  <pre><code>-(void)typeTapped:(id)sender
  {
     UIButton* btn = (UIButton)sender;
     //download image from network in ohter thread and change button' image.
     NSThread * thread = [Thread alloc] initWith:@selecter(downloadImage:)....
     [thread start];
     [thread release];
  }
  //download image 
  -(void)downloadImage:(UIButton*)btn....
  {
    //download
    UIImage* image= ....
    //UITableView is not update
    //it is will update when i scroll tableview.
    [btn setImage:image ......];
  }
  </code></pre>
  
  <p>so how can i update UITableViewCell in other thread.(if i call reloadDate it is will drop-dead halt)(i can scroll tableview to update it)</p>