ASINetworkQueue使用cancelAllOperations方法来取消下载时使用的注意点在 ASIHTTPRequest V1.7前提下正确使用： imgDataDownLo

本文介绍在使用ASINetworkQueue进行文件下载时，如何正确地取消所有下载任务以避免程序崩溃。通过对比两种不同设置方式的结果，指导开发者如何在对象释放时安全地取消下载操作。

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ASINetworkQueue使用cancelAllOperations方法来取消下载时使用的注意点

在 ASIHTTPRequest V1.7前提下

正确使用：
   imgDataDownLoadQueue = [[ASINetworkQueue alloc] init];
   [imgDataDownLoadQueue setShouldCancelAllRequestsOnFailure:NO];
   [imgDataDownLoadQueue setDelegate:self];
   [imgDataDownLoadQueue setRequestDidFailSelector:@selector(imgDataRequestFail:)];
   [imgDataDownLoadQueue setRequestDidFinishSelector:@selector(imgDataRequestFinish:)];
   [imgDataDownLoadQueue setQueueDidFinishSelector:@selector(imgDataQueueDidFinish:)];

    for(int i=0; i<[imgDatasToLoadArray count]; i++)
    {
     ASIHTTPRequest* imgRq = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:[[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"imgurl"]]];

     NSString* value[2];
     NSString* key[2];
     value[0] = [[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"imgtime"];
     value[1] = [[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"index"];
     key[0] = @"imgtime";
     key[1] = @"index";

     imgRq.userInfo = [NSDictionary dictionaryWithObjects:value forKeys:key count:2];

     [imgDataDownLoadQueue addOperation:imgRq];
    }
    [imgDataDownLoadQueue go];

=======
这样在dealloc中取消下载
[imgDataDownLoadQueue setDelegate:nil];
[imgDataDownLoadQueue cancelAllOperations];
[imgDataDownLoadQueue release];
imgDataDownLoadQueue = nil;
不会导致crash.

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如果按这种方法使用：

   imgDataDownLoadQueue = [[ASINetworkQueue alloc] init];
   [imgDataDownLoadQueue setShouldCancelAllRequestsOnFailure:NO];
   [imgDataDownLoadQueue setDelegate:self];

    for(int i=0; i<[imgDatasToLoadArray count]; i++)
    {
     ASIHTTPRequest* imgRq = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:[[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"imgurl"]]];

     NSString* value[2];
     NSString* key[2];
     value[0] = [[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"imgtime"];
     value[1] = [[imgDatasToLoadArray objectAtIndex:i] objectForKey:@"index"];
     key[0] = @"imgtime";
     key[1] = @"index";

     imgRq.userInfo = [NSDictionary dictionaryWithObjects:value forKeys:key count:2];
     [imgRq setRequestDidFailSelector:@selector(imgDataRequestFail:)];
   [imgRq setRequestDidFinishSelector:@selector(imgDataRequestFinish:)];

     [imgDataDownLoadQueue addOperation:imgRq];
    }
    [imgDataDownLoadQueue go];