我的圖像視圖在表格視圖中行爲不正確？

Question

我有以下方式加載表視圖。如果符合條件，我需要在cell.imageview上方添加特定圖像。此外，圖像來自不同的維度。下面是我的代碼，任何人都可以指出我錯在哪裏。

static NSString *CellIdentifier = @"Cell"; 

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
if (cell == nil) { 
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease]; 
} 
if(array==nil||[array count]==0) 
{ 

} 
else 
{ 
    NSMutableDictionary *dicttable=[array objectAtIndex:indexPath.row]; 
    NSString *head=[dicttable objectForKey:@"name"]; 
    NSString *type=[dicttable objectForKey:@"type"]; 

    NSString *imgUrl = [dicttable objectForKey:@"image"];; 
    if(imgUrl!=nil) 
    { 
     if(![[ImageCache sharedImageCache] hasImageWithKey:imgUrl]) 
     { 
      cell.imageView.image = [UIImage imageNamed:@"noimage_icon.png"]; 
      NSArray *myArray = [NSArray arrayWithObjects:cell.imageView,imgUrl,@"noimage_icon.png",[NSNumber numberWithBool:NO],nil]; 
      AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate]; 
      [appDelegate performSelectorInBackground:@selector(updateImageViewInBackground:) withObject:myArray]; 
      cell.imageView.frame=CGRectMake(0,0,48,48); 
      cell.imageView.bounds=CGRectMake(0,0,48,48); 
      [cell.imageView setClipsToBounds:NO]; 
     } 
     else 
     { 
      cell.imageView.image = [[ImageCache sharedImageCache] getImagefromCacheOrUrl:imgUrl]; 
      cell.imageView.frame=CGRectMake(0,0,48,48); 
      cell.imageView.bounds=CGRectMake(0,0,48,48); 
      [cell.imageView setClipsToBounds:NO]; 
     } 
    } 
    else 
    { 
     cell.imageView.image = [UIImage imageNamed:@"noimage_icon.png"]; 
    } 
    if([type isEqualToString:@"YES"]) 
    { 
     UIImageView* img = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"bluel.png"]]; 
     [cell setBackgroundView:img]; 
     [img release]; 

     cell.textLabel.text = head; 
     cell.textLabel.backgroundColor = [UIColor clearColor]; 

     cell.detailTextLabel.textColor=[UIColor grayColor]; 
     cell.detailTextLabel.text = subtitle1; 
     cell.detailTextLabel.backgroundColor = [UIColor clearColor]; 
    } 
    else 
    { 
     UIImageView* img = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"wnew1.png"]]; 
     [cell setBackgroundView:img]; 
     [img release]; 
     cell.textLabel.text = head; 
     cell.textLabel.backgroundColor = [UIColor clearColor]; 
     [cell.imageView addsubview:spclimage] 

     cell.textLabel.text = head; 
     cell.textLabel.backgroundColor = [UIColor clearColor]; 

     cell.detailTextLabel.textColor=[UIColor grayColor]; 
     cell.detailTextLabel.text = subtitle1; 
     cell.detailTextLabel.backgroundColor = [UIColor clearColor];    
    } 
} 
return cell; 

這裏問題只出現在特殊圖像的最後一行添加。不是全部行。此外，圖像視圖大小在重新加載tableview的所有時間都不相同。

Answer 1

一對夫婦的想法：

1. 的updateImageViewInBackground看來犯罪嫌疑人，顧名思義，你更新的形象圖，但不指定要更新哪個小區。

2. 我也看到你在做一個addSubview:spclimage。很顯然，如果spclimage在另一個單元格上，那麼只要您做了addSubview，它就會在添加到當前單元格之前從先前的位置移除。實際上，只是將圖像添加爲現有圖像視圖的子視圖的想法很好奇。

3. 如果你的緩存還沒有圖像，我看到你在用noimage_icon.png初始化圖像，但是我沒有看到你實際更新圖像視圖的位置。你說updateImageViewInBackground是「然後更新圖像」。你的意思是爲設置image屬性爲imageView這個indexPath？或者可能更新spclimage？如果是這樣，這是有問題的。

4. 典型模式（使用GCD），因爲這將是：

   cell.imageView.image = [UIImage imageNamed:@"noimage_icon.png"]; 
   
   dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ 
       UIImage *image = ... // do whatever you need to do to get the image, load cache, etc. 
   
       // ok, now that you have the image, dispatch the update of the UI back to the main queue 
   
       dispatch_async(dispatch_get_main_queue(), ^{ 
   
        // because we're doing this asynchronously, make sure the cell is still 
        // visible (it could have scrolled off and the cell was dequeued and 
        // reused), so we're going to ask the tableview for the cell for that 
        // indexPath, and it returns `nil` if it's not visible. This method is 
        // not to be confused with the similarly named `UITableViewControllerDelegate` 
        // method. 
   
        UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; 
   
        // if the image view is still visible, update it 
   
        if (cell) 
        { 
         cell.imageView.image = image; 
        }  
       }); 
   
   });