从背景加载图片

我在后台加载图片。使用此代码从背景加载图片

-(void)backgroundImageLoading 
{ 
    if(isGroupOrFriend) 
    { 
     NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init]; 

     for(NSDictionary *d in m_kwikiArray) 
     { 
      NSMutableDictionary *dict=[NSMutableDictionary dictionary]; 
      if([d valueForKey:@"UserImage"]!=nil && ![[d valueForKey:@"UserImage"] isEqualToString:@""]) 
      { 
       UIImage *img=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[d valueForKey:@"UserImage"]]]]; 
       if(img!=nil) 
        [dict setObject:img forKey:@"UserImage"]; 
      } 
      else 
       [dict setObject:@"No Image" forKey:@"UserImage"]; 
      //if([d valueForKey:@"imagePath"]!=nil && ![[d valueForKey:@"imagePath"] isEqualToString:@""]) 
      //   [dict setObject:[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[d valueForKey:@"imagePath"]]]] forKey:@"imagePath"]; 
      //  else 
      //   [dict setObject:@"NO Image" forKey:@"imagePath"]; 
      if([[d valueForKey:@"Transactions"] count]>0) 
      { 
       if([[[d valueForKey:@"Transactions"] objectAtIndex:0] valueForKey:@"UserThumbnail"]!= nil && ![[[[d valueForKey:@"Transactions"] objectAtIndex:0]valueForKey:@"UserThumbnail"] isEqualToString:@""]) 
       { 
        UIImage *img1=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[[d valueForKey:@"Transactions"] objectAtIndex:0] valueForKey:@"UserThumbnail"]]]]; 
        if(img1!=nil) 
         [dict setObject:img1 forKey:@"UserThumbnail1"]; 
       } 
       else 
        [dict setObject:@"NOImage" forKey:@"UserThumbnail1"]; 
      } 
      else 
       [dict setObject:@"NOImage" forKey:@"UserThumbnail1"]; 
      if([[d valueForKey:@"Transactions"] count]>1) 
      { 
       if([[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"]!=nil && ![[[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"] isEqualToString:@""]) 
       { 
        UIImage *img2=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"]]]]; 
        if(img2!=nil) 
         [dict setObject:img2 forKey:@"UserThumbnail2"]; 
       } 
       else 
        [dict setObject:@"NOImage" forKey:@"UserThumbnail2"]; 
      } 
      else 
       [dict setObject:@"NOImage" forKey:@"UserThumbnail2"]; 
      [imageForGruopAndFriendArray addObject:dict]; 

     } 
     //isReloadTable=YES; 
     [mTable reloadData]; 
     [pool release]; 
    } 
    else 
    { 
     NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init]; 

     for(NSDictionary *d in m_kwikiArray) 
     { 
      NSMutableDictionary *dict=[NSMutableDictionary dictionary]; 
      if([d valueForKey:@"Illustration"]!=nil && ![[d valueForKey:@"Illustration"] isEqualToString:@""]) 
      { 
       UIImage *img=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[d valueForKey:@"Illustration"]]]]; 
       if(img!=nil) 
        [dict setObject:img forKey:@"Illustration"]; 
      } 

      else 
       [dict setObject:@"No Image" forKey:@"Illustration"]; 
      if([d valueForKey:@"imagePath"]!=nil && ![[d valueForKey:@"imagePath"] isEqualToString:@""]) 
      { 
       UIImage *img1=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[d valueForKey:@"imagePath"]]]]; 
       if(img1!=nil) 
        [dict setObject:img1 forKey:@"imagePath"]; 
      } 
      else 
       [dict setObject:@"NO Image" forKey:@"imagePath"]; 
      if([[d valueForKey:@"Transactions"] count]>0) 
      { 
       if([[[d valueForKey:@"Transactions"] objectAtIndex:0] valueForKey:@"UserThumbnail"]!= nil && ![[[[d valueForKey:@"Transactions"] objectAtIndex:0]valueForKey:@"UserThumbnail"] isEqualToString:@""]) 
       { 

        UIImage *img2=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[[d valueForKey:@"Transactions"] objectAtIndex:0] valueForKey:@"UserThumbnail"]]]]; 
        if(img2!=nil) 
         [dict setObject:img2 forKey:@"UserThumbnail1"]; 
       } 
       else 
        [dict setObject:@"NOImage" forKey:@"UserThumbnail1"]; 
      } 
      else 
       [dict setObject:@"NOImage" forKey:@"UserThumbnail1"]; 
      if([[d valueForKey:@"Transactions"] count]>1) 
      { 
       if([[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"]!=nil && ![[[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"] isEqualToString:@""]) 
       { 
        UIImage *img3=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[[d valueForKey:@"Transactions"] objectAtIndex:1] valueForKey:@"UserThumbnail"]]]]; 
        if(img3!=nil) 
         [dict setObject:img3 forKey:@"UserThumbnail2"]; 
       } 
       else 
        [dict setObject:@"NOImage" forKey:@"UserThumbnail2"]; 
      } 
      else 
       [dict setObject:@"NOImage" forKey:@"UserThumbnail2"]; 
      [imageArray addObject:dict]; 

     } 
     //isReloadTable=YES; 
     [mTable reloadData]; 
     [pool release]; 
    } 
}

这里我使用reloadData每个图片加载后的方法，但它不会加载图片滚动表后显示。

我想在加载后立即显示这些图像。

请帮帮我。提前Thanx。

来源

2011-06-09 Ishu

你们是不是比主线程之外的其他线程更新UI？ – 2011-06-09 07:37:39

在代码中加入这一行insted的的[m_Table reloadData];我用这条线

[m_Table performSelectorOnMainThread:@selector(reloadData) withObject:self waitUntilDone:NO];

来源

2011-06-10 04:53:40 Ishu

Ishu，

尝试使用它代替的[mTable reloadData]：

[mTable beginUpdates]; 
[mTable endUpdates];

顺便说一句，不好意思说，但是这个代码是完全不可读。

来源

2011-06-09 07:38:28 Zapko

这不工作仍然需要滚动显示在表中的图像。 – Ishu 2011-06-09 08:01:34

我完全同意Zapko - 你的代码是不可读的。 – 2011-06-09 08:09:49

Ishu，您的代码的基本问题是，您无法通过UIImage imageWithData API在辅助线程中加载图像。 UIKit APIS只能在主线程中使用。你可以做的是下载项目并将它们保存到辅助线程中的文件中，但是仍然需要在主线程中加载该图像数据。如果您只是想下载并加载图像数据，您甚至不需要辅助线程，因为NSURLConnection类已经支持异步完成回调，下载会自动在后台线程中完成。

来源

2011-06-09 20:11:14 MoDJ

你说得对。我已经解决了我的问题，看到我的答案。 – Ishu 2011-06-10 04:51:46

从背景加载图片

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