ios - 由于多线程代码导致内存压力而终止

Question

我的应用程序在使用过程中的某个时刻由于内存压力而终止，我已将问题隔离为导致问题的一段代码。

我将复制下面的代码(我已经通过注释掉这段代码并运行应用程序进行了测试，应用程序运行良好)。

我在这里要做的是:我正在阅读 RSS 提要，获取图像的 URL 并将其显示在 tableView 单元格中。下面的代码来自 cellForRowAtIndexPath。

// 1. Check the image cache to see if the image already exists. If so, then use it. If not, then download it.
    if ([[ImageCache sharedImageCache] DoesExist:imgSrcString] == true)
    {
        cell.cellImageView.image = [[ImageCache sharedImageCache] GetImage:imgSrcString];
    } else {
        cell.cellImageView.image = [UIImage imageNamed:@"NoImage_Small"];
        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0ul);
        // Now, we can’t cancel a block once it begins, so we’ll use associated objects and compare
        // index paths to see if we should continue once we have a resized image.
        objc_setAssociatedObject(cell,
                                 kIndexPathAssociationKey,
                                 indexPath,
                                 OBJC_ASSOCIATION_RETAIN);

        dispatch_async(queue, ^{
            NSData * imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imgSrcString]];
            UIImage *image = [UIImage imageWithData:imageData];
            //UIImage *resizedImage = [image scaleToSize:CGSizeMake(71.0f,71.0f)] ; //[UIImage resizeImage];
            dispatch_async(dispatch_get_main_queue(), ^{
                NSIndexPath *cellIndexPath =
                (NSIndexPath *)objc_getAssociatedObject(cell, kIndexPathAssociationKey);
                if(image){
                    if ([indexPath isEqual:cellIndexPath]) {
                        [[cell cellImageView] setImage:image];
                        [[ImageCache sharedImageCache] AddImage:imgSrcString :image];
                    }
                }

                // [[ImageCache sharedImageCache] AddImage:[imgSrcString stringByAppendingString:@"bigImage"] :image];
            });
        });
    }

如果能帮我指明正确的方向，我们将不胜感激。感谢您的宝贵时间!

Answer 1

关于这个问题我已经上网了。顺便说一句，在一些博客中他们提到默认 NSURLConnection 包含根本不清楚的缓存。这可能就是坠机的原因。所以尝试使用 ASIHTTPRequest http://allseeing-i.com/ASIHTTPRequest/那么你就永远不会感觉到有关图像下载的内存警告。

使用此代码进行 ASIHTTPRequest 集成(添加 sdk 文件后)

-(void)resetNetworkQueue
{
    // initialising network queue.
    self.networkQueue =[[ASINetworkQueue alloc]init];

    [self.networkQueue setRequestDidFinishSelector:@selector(mediaDownloadCompleted:)];
    [self.networkQueue setRequestDidFailSelector:@selector(mediaDownloadFailed:)];
    [self.networkQueue setRequestDidStartSelector:@selector(mediaDownloadStarted:)];
    [self.networkQueue setQueueDidFinishSelector:@selector(networkQueueCompletedProcess:)];
    [self.networkQueue setMaxConcurrentOperationCount:10];
    [self.networkQueue setShouldCancelAllRequestsOnFailure:NO];

    [self.networkQueue setDelegate:self];

}


-(void)createDownloadRequest
{
  //Adding request in network queue.
  self.request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:imageURL]];
    [self.request setDownloadDestinationPath:downloadDestinationPath];
    [self.request setDelegate:self];
    [self.request setAllowResumeForFileDownloads:YES];
    [self.request setTimeOutSeconds:30];
    [self.networkQueue addOperation:self.request];
    [self.request setUserInfo:[NSDictionary dictionaryWithObjectsAndKeys:homeInfo,@"FloorPlanInfo",imageType,@"ImageType", nil]];
}



- (void)mediaDownloadStarted:(ASIHTTPRequest *)request
{
   //Fire when request started. 
}
- (void)mediaDownloadCompleted:(ASIHTTPRequest *)request
{

     //Fire when request completed. 
}
- (void)mediaDownloadFailed:(ASIHTTPRequest *)request
{
    //Fire when request Failed to download. 
}