表视图与异步图像加载代理怪异

我有一个表视图与背景视图和一些文字。我正在从一个url下载背景（在下面的代码中它是硬编码的，但我将为每个单元格设置不同的url）。为了改善响应，我使用图像缓存来保存下载的图像并异步加载图像。如果我滚动，图像会调整到每个单元中的其他东西，如果我停止滚动，我可以看到图像随机刷新在每个单元有时像刚刚消失，几秒钟后再次出现表视图与异步图像加载代理怪异

我不够好于iOS的图了这一点请大家帮

这里是我的手机数据源的方法：。

- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    if(indexPath.row==0){ 
     UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"identifier"]; 
     [cell.contentView addSubview:self.headerFrame]; 
     cell.selectionStyle = UITableViewCellSelectionStyleNone; 
     return cell; 
    } 
    static NSString *cellIdentifier = @"HistoryCell"; 
    // Similar to UITableViewCell, but 
    CustomSaloonCell *cell = (CustomSaloonCell *)[theTableView dequeueReusableCellWithIdentifier:cellIdentifier]; 
    if (cell == nil) { 
     cell = [[CustomSaloonCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; 
     cell.selectionStyle = UITableViewCellSelectionStyleNone; 
    } 

    NSString *identifier = [NSString stringWithFormat:@"Cell%ld" , 
          (long)indexPath.row]; 
    if([self.cachedImages objectForKey:identifier] != nil){ 
     cell.backgroundView = [[UIImageView alloc]initWithImage:[cachedImages valueForKey:identifier]]; 
    } 
    else { 
     char const * s = [identifier UTF8String]; 
     dispatch_queue_t queue = dispatch_queue_create(s, 0); 
     dispatch_async(queue, ^{ 
      NSURL *url = [NSURL URLWithString:@"http://upload.wikimedia.org/wikipedia/en/thumb/7/73/Shrekcharacter.jpg/220px-Shrekcharacter.jpg"]; 
      UIImage *img = nil; 
      NSData *data = [[NSData alloc] initWithContentsOfURL:url]; 
      img = [[UIImage alloc] initWithData:data]; 
      dispatch_async(dispatch_get_main_queue(), ^{ 
       if ([theTableView indexPathForCell:cell].row == indexPath.row) { 
        [cachedImages setValue:img forKey:identifier]; 
        cell.backgroundView = [[UIImageView alloc]initWithImage:[cachedImages valueForKey:identifier]]; 
        cell.backgroundView.alpha = 0.0; 
        [UIView animateWithDuration:5.0 animations:^{ 
         cell.backgroundView.alpha = 1.0; 
        }]; 
       } 
      }); 
     }); 
    } 
    /********/ 
    cell.stylistName.text = [salonDetailsArray objectAtIndex:indexPath.row][@"salonName"]; 
    cell.salonAddress.text = [salonDetailsArray objectAtIndex:indexPath.row][@"salonAddress"]; 
    cell.delegateListener = self; 
    cell.claimButton.frame =CGRectMake(494/2, 216/2, 120/2, 46.0/2.0); 
    [cell.claimButton addTarget:self action:@selector(claimClicked:) forControlEvents:UIControlEventTouchUpInside]; 
    [cell.claimButton setTitle:@"claim" forState:UIControlStateNormal]; 
    if([loginStatus isEqualToString:@"YES"]){ 
     [cell.claimButton setTitleColor:[UIColor colorWithRed:106.0/255.0 green:45.0/255.0 blue:118.0/255.0 alpha:1.0] forState:UIControlStateNormal]; 
    }else { 

     [cell.claimButton setTitleColor:[UIColor grayColor] forState:UIControlStateNormal]; 
    } 

    cell.claimButton.tag = indexPath.row; 
    cell.overlay.hidden = YES; 
    for (NSIndexPath *selectedIndex in self.buttonStateArray){ 
     if([selectedIndex isEqual:indexPath]){ 
      [cell.claimButton setTitle:@"claimed" forState:UIControlStateNormal]; 
       cell.claimButton.frame = CGRectMake(464/2-(30/2), 216/2, 180/2, 46.0/2.0); 
      cell.overlay.hidden = NO; 
      [cell.claimButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal]; 
     } 
    } 
    return cell; 
}

来源

2014-02-10 user2810114

这是SO上的第二个问题。搜索更难时你会找到有价值的答案。 ;）主要的问题是你正在捕获你的完成处理程序中的_cell_ - 可能在处理程序被执行的同时被重用（相反，捕获_indexPath_并再次获取单元格！）。您还应该使用适当的方法来加载远程资源。 – CouchDeveloper