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我已经阅读了大多数与 AFNetworking 的异步性质有关的帖子。但是，我的问题有点独特，我可以使用一些帮助。

我正在从模态视图控制器启动一个新的异步线程，该线程应该告诉用户我正在从 Web 服务器下载内容。这个想法是下载一堆文件（超过 100 个），效果很好。我什至将重试计数放入下载中，以便在失败时重试下载任何文件（最多）。一切都很好下载。问题是我不知道什么时候完成。

原因如下：我正在下载 JSON 文件列表。这些 JSON 文件定义了具有 PDF 和其他类型文件列表的其他 JSON 文件列表。由于我正在下载的内容的性质，我必须按顺序下载它。例如：

  1. 下载文件1.json
  2. 下载后从 file1.json 获取 JSON 文件列表
  3. 加载每个辅助 JSON 文件（subFile1.json、subFile2.json 等）
  4. 下载辅助 JSON 文件 (subFile1.json) 后，我会从该 JSON 文件 (subFile1.json) 中获取要下载的文件列表
  5. 下载 JSON 子文件中指定的每个文件（例如 subFile1.json）

所以我的过程看起来是分层的，以确保在子文件之前下载父文件： 1. 初始下载方法在成功时调用 SubDownloadMethod2（在成功块内） 2. SubDownloadMethod2 从下载的文件中获取列表并调用 SubSubDownloadMethod3 3. SubSubDownloadMethod3 下载 PDF 文件（和其他文件） ) ON SUCCESS (在成功块内)

如您所见，我有动态数量的文件要下载。因此我不知道我会预先下载多少文件。由于它可以进入多个级别并来自 Web 服务器上的多个目录，因此它变得更加困难。

如果下载失败（达到最大重试次数），我也会对每个方法进行递归回调，这也使它变得更加困难。

因为每次下载都会启动它自己的线程（我假设这就是 AFNetworking 正在做的事情），所以我不确定所有下载何时完成。我不知道 enqueueBatchOfHTTPRequestOperations 是否有帮助。我不完全理解它，我正在从网络服务器上的多个目录下载。我还需要根据每个下载级别进行批处理操作，因为我不知道在下载和解析定义的 JSON 文件之前我会走多远。

帮助！！！！

我认为将代码放入其中可能会有所帮助。要查看的代码很多，但这是一个难题（嗯，对于具有我技能的人来说）。

如果你看代码，每次我需要下载另一个文件时，我都会调用最底部的方法：

- (void)downloadLibraryFile:(NSString *)fileOnServer targetFile:(NSString *)targetFile retryCount:(int)retryCount completionBlock:(DownloadLibraryFileCompletionBlock)completionBlock
{
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:fileOnServer]];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:targetFile append:NO];

[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
    {
         //NSLog(@"Successfully downloaded file to %@", path);
         completionBlock(fileOnServer, targetFile, retryCount, nil);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
         completionBlock(fileOnServer, targetFile, retryCount, error);
    }];

[operation start];
}

这将启动 AFNetorking 并开始下载。完成后它会调用我的完成块，但我怎么知道它们什么时候完成？

这是剩下的代码（包括上面的方法）

- (void)downloadLibraryOnReset
{
// Find and copy the page defintion file to the documents directoy
// TODO localize the call to get the appropriate file based on language
dispatch_queue_t queue = dispatch_queue_create("Library Download Queue", NULL);
dispatch_async(queue, ^{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *serverLibraryURL = [defaults objectForKey:kRootURL];
    serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:kPageDefinitionsDirectory];

    // Save server root URL
    self.serverRootURL = serverLibraryURL;

    // Add last component onto download path
    serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:kPageDefinitions];

    // Get target location
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);;
    NSString *targetFile = [dirPaths objectAtIndex:0];
    targetFile = [targetFile stringByAppendingPathComponent:@"en"]; // TODO this needs to be localized based on language
    targetFile = [targetFile stringByAppendingPathComponent:kPageDefinitionsDirectory];
    self.pageDefintiionDirectoryURL = targetFile;
    // Create the subdirectory off of the documents directory to contain the config files
    NSFileManager *filemgr = [NSFileManager defaultManager];
    if ([filemgr createDirectoryAtPath:targetFile withIntermediateDirectories:YES attributes:nil error: NULL] == NO)
    {
        // Failed to create directory
    }

    NSString *pageDefinitionsFileURL = [targetFile stringByAppendingPathComponent:kPageDefinitions];

    [self downloadPageDefinitionsFile:serverLibraryURL targetFile:pageDefinitionsFileURL retryCount:kDownloadRetryCount];

    // Reset the resetContent flag to false
    [defaults setBool:NO forKey:kResetContent];
});
}

- (void)downloadPageDefinitionsFile:(NSString *)fileOnServer targetFile:(NSString *)targetFile retryCount:(int)retryCount
{
[self downloadLibraryFile:fileOnServer targetFile:targetFile retryCount:retryCount completionBlock:^(NSString *fileOnServer, NSString *targetFile, int retryCount, NSError *error) {
    if(error)
    {
        retryCount--;
        if(retryCount)
        {
            NSLog(@"RETRY DONWLOAD (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), fileOnServer);
            [self downloadPageDefinitionsFile:fileOnServer targetFile:targetFile retryCount:retryCount];
        }
        else
        {
            NSLog(@"RETRY COUNT EXCEEDED (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount, NSStringFromSelector(_cmd), fileOnServer);
        }
    }
    else
    {
        // Check to see if this file was downloaded after an error
        if(retryCount < kDownloadRetryCount)
        {
            NSLog(@">>RETRY SUCCESSFUL (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), fileOnServer);
        }

        // Copy down all config files defined in the pagedefinitions.json file
        //code from other library
        NSError* err = nil;

        NSString *path = self.pageDefintiionDirectoryURL;
        path = [path stringByAppendingPathComponent:kPageDefinitions];

        NSData *data = [NSData dataWithContentsOfFile:path];

        if(data)
        {
            // Convert to JSON Directory
            NSMutableDictionary *pageDefinitionsDict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&err];

            //fileVersion = pageDefinitionsDict[kFileVersion];
            NSMutableArray *pages = pageDefinitionsDict[kPages];
            for (NSMutableDictionary *page in pages)
            {
                MINPageDefinition *pageDef = [[MINPageDefinition alloc] initWithDictionary:page];
                NSString *targetDirectory = [targetFile stringByDeletingLastPathComponent];
                pageDef.pageURL = [targetDirectory stringByAppendingPathComponent:pageDef.pageConfigFileName];

                //NSString *imageURL = [pageDef.pageURL stringByDeletingLastPathComponent];
                pageDef.pageImageURL = [self.pageDefintiionDirectoryURL stringByAppendingPathComponent:pageDef.pageImageName];

                [[MINPageStore sharedInstance].pageArray addObject:pageDef];
            }
            // Write modified pagedefinitions.json to the appropriate directory in Documents
            [[MINPageStore sharedInstance] writePageDefinitionFile:path];

            // Continue downloading page images and other config files,
            for (MINPageDefinition *currPage in [[MINPageStore sharedInstance] pageArray])
            {
                [self downloadPageDefinitionImageFile:currPage retryCount:kDownloadRetryCount];
                [self downloadPageDefinitionJSONFile:currPage retryCount:kDownloadRetryCount];
            }
        }
    }
}];
}

- (void)downloadPageDefinitionJSONFile:(MINPageDefinition *)pageDef retryCount:(int)retryCount
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *serverLibraryURL = [defaults objectForKey:kRootURL];
serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:kPageDefinitionsDirectory];
serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:pageDef.pageConfigFileName];

[self downloadLibraryFile:serverLibraryURL targetFile:pageDef.pageURL retryCount:retryCount completionBlock:^(NSString *fileOnServer, NSString *targetFile, int retryCount, NSError *error) {

    if(error)
    {
        retryCount--;
        if(retryCount)
        {
            NSLog(@"RETRY DONWLOAD (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), serverLibraryURL);
            [self downloadPageDefinitionJSONFile:pageDef retryCount:retryCount];
        }
        else
        {
            NSLog(@"RETRY COUNT EXCEEDED (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount, NSStringFromSelector(_cmd), serverLibraryURL);
        }
    }
    else
    {
        // Check to see if this file was downloaded after an error
        if(retryCount < kDownloadRetryCount)
        {
            NSLog(@">>RETRY SUCCESSFUL (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), serverLibraryURL);
        }

        // Copy down all config files defined in the pagedefinitions.json file
        if([pageDef.pageType isEqualToString:kGridView])
        {
            [self downloadGridViewContent:pageDef];
        }
        else
        {
            //NSLog(@">>>>FINISHED DOWNLOADING PAGE: %@", pageDef.pageName);
        }

    }
}];
}

- (void)downloadPageDefinitionImageFile:(MINPageDefinition *)pageDef retryCount:(int)retryCount
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *serverLibraryURL = [defaults objectForKey:kRootURL];
serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:kPageDefinitionsDirectory];
serverLibraryURL = [serverLibraryURL stringByAppendingPathComponent:pageDef.pageImageName];

[self downloadLibraryFile:serverLibraryURL targetFile:pageDef.pageImageURL retryCount:retryCount completionBlock:^(NSString *fileOnServer, NSString *targetFile, int retryCount, NSError *error) {
    if(error)
    {
        retryCount--;
        if(retryCount)
        {
            NSLog(@"RETRY DONWLOAD (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), serverLibraryURL);
            [self downloadPageDefinitionImageFile:pageDef retryCount:retryCount];
        }
        else
        {
            NSLog(@"RETRY COUNT EXCEEDED (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount, NSStringFromSelector(_cmd), serverLibraryURL);
        }
    }
    else
    {
        // Check to see if this file was downloaded after an error
        if(retryCount < kDownloadRetryCount)
        {
            NSLog(@">>RETRY SUCCESSFUL (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), serverLibraryURL);
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.masterViewController.tableView reloadData];
        });
    }

}];
}

- (void)downloadGridViewContent:(MINPageDefinition *)pageDef
{
// Parse off the json extension
// Use this to create a subdirectory under the pagedefinitions directoy
NSString *newDirectoryForGridView = [pageDef.pageURL stringByDeletingPathExtension];
newDirectoryForGridView = [newDirectoryForGridView lastPathComponent];
NSString *newGridViewDirectoryURL = [pageDef.pageURL stringByDeletingPathExtension];

// Create the subdirectory off of the documents directory to contain the config files
NSFileManager *filemgr = [NSFileManager defaultManager];
if ([filemgr createDirectoryAtPath:newGridViewDirectoryURL withIntermediateDirectories:YES attributes:nil error: NULL] == NO)
{
    // Failed to create directory
}

// Load the grid view config file
[MINVolume loadAlbumItems:pageDef.pageURL completionBlock:^(NSString *fileName, MINVolume *newVolume, NSError *error) {
    if(!error)
    {
        if(newVolume && [newVolume.albumsArray count] > 0)
        {
            // Iterate through the albums and create directories for each album
            for(MINAlbum *album in newVolume.albumsArray)
            {
                NSString *localAlbumDirectory = [newGridViewDirectoryURL stringByAppendingPathComponent:album.albumURL];
                if ([filemgr createDirectoryAtPath:localAlbumDirectory withIntermediateDirectories:YES attributes:nil error: NULL] == NO)
                {
                    // Failed to create directory
                }
                // Copy down all album content
                for(MINAlbumItem *albumItem in album.albumItemsArray)
                {
                    // Create names for local file and thumbnail
                    NSString *localAlbumItemFileURL = [localAlbumDirectory stringByAppendingPathComponent:albumItem.itemFileName];
                    NSString *localAlbumItemFileThumbURL = [localAlbumDirectory stringByAppendingPathComponent:albumItem.itemThumbnailImageName];

                    // Define paths for file and thumbnail on server
                    NSString *serverAlbumItemFileURL = [self.serverRootURL stringByAppendingPathComponent:newDirectoryForGridView];
                    serverAlbumItemFileURL = [serverAlbumItemFileURL stringByAppendingPathComponent:album.albumURL];
                    serverAlbumItemFileURL = [serverAlbumItemFileURL stringByAppendingPathComponent:albumItem.itemFileName];
                    NSString *serverAlbumItemFileThumbURL = [self.serverRootURL stringByAppendingPathComponent:newDirectoryForGridView];
                    serverAlbumItemFileThumbURL = [serverAlbumItemFileThumbURL stringByAppendingPathComponent:album.albumURL];
                    serverAlbumItemFileThumbURL = [serverAlbumItemFileThumbURL stringByAppendingPathComponent:albumItem.itemThumbnailImageName];

                    // Copy album item file
                    BOOL bFileExists = [filemgr fileExistsAtPath:localAlbumItemFileURL];
                    if(!bFileExists)
                    {
                        [self downloadAlbumItem:albumItem isThumbnail:(BOOL)false fileOnServer:serverAlbumItemFileURL targetFile:localAlbumItemFileURL retryCount:kDownloadRetryCount];
                    }
                    else
                    {
                        albumItem.itemURL = localAlbumItemFileURL;
                    }

                    // Copy album item thumbnail
                    BOOL bFileThumbnailExists = [filemgr fileExistsAtPath:localAlbumItemFileThumbURL];
                    if(!bFileThumbnailExists)
                    {
                        [self downloadAlbumItem:albumItem isThumbnail:true fileOnServer:serverAlbumItemFileThumbURL targetFile:localAlbumItemFileThumbURL retryCount:kDownloadRetryCount];
                    }
                    else
                    {
                        albumItem.itemThumbnailURL = localAlbumItemFileThumbURL;
                    }
                }
            }
        }
        else
        {
            NSLog(@"No volume found for file: %@", pageDef.pageConfigFileName);
        }
    }
}];
}

- (void)downloadAlbumItem:(MINAlbumItem *)albumItem isThumbnail:(BOOL)isThumbnail fileOnServer:(NSString *)fileOnServer targetFile:(NSString *)targetFile retryCount:(int)retryCount
{
[self downloadLibraryFile:fileOnServer targetFile:targetFile retryCount:retryCount completionBlock:^(NSString *fileOnServer, NSString *targetFile, int retryCount, NSError *error) {
    if(error)
    {
        retryCount--;
        if(retryCount)
        {
            NSLog(@"RETRY DONWLOAD (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), fileOnServer);
            [self downloadAlbumItem:albumItem isThumbnail:isThumbnail fileOnServer:fileOnServer targetFile:targetFile retryCount:retryCount];
        }
        else
        {
            NSLog(@"RETRY COUNT EXCEEDED (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount, NSStringFromSelector(_cmd), fileOnServer);
        }
    }
    else
    {
        // Check to see if this file was downloaded after an error
        if(retryCount < kDownloadRetryCount)
        {
            NSLog(@">>RETRY SUCCESSFUL (Attempt: %d, Method: %@) > File: %@", kDownloadRetryCount - retryCount, NSStringFromSelector(_cmd), fileOnServer);
        }

        if(isThumbnail)
            albumItem.itemThumbnailURL = targetFile;
        else
            albumItem.itemURL = targetFile;
    }
}];
}

- (void)downloadLibraryFile:(NSString *)fileOnServer targetFile:(NSString *)targetFile retryCount:(int)retryCount completionBlock:(DownloadLibraryFileCompletionBlock)completionBlock
{
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:fileOnServer]];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:targetFile append:NO];

[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
    {
         //NSLog(@"Successfully downloaded file to %@", path);
         completionBlock(fileOnServer, targetFile, retryCount, nil);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
         completionBlock(fileOnServer, targetFile, retryCount, error);
    }];

[operation start];
}
4

3 回答 3

0

如果您正在执行 AFHTTPRequestOperation，则可以使用它的 setCompletionBlockWithSuccess 方法设置一个块，一旦下载（甚至上传）完成，就会调用该块。

例子：

AFHTTPRequestOperation *httpreq = [[AFHTTPRequestOperation alloc] initWithRequest:[NSURLRequest requestWithURL:downloadURL]];
[httpreq setCompetionBlockWithSuccess^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"%@",@"Done!");
}];

此外，您不需要在不同的线程中启动操作，因为它已经异步运行。

于 2013-01-06T05:38:28.540 回答
0

您在 NSOperationQueue 中添加所有操作，如下所示：

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation: operation]; //your operation here
[operation start] 
[operation waitUntilFinish]

如何维护 NSOperationQueue 请参考以下链接：

请参阅ios-how-to-know-when-nsoperationqueue-finish-processing-a-few-operations链接。

请参阅ios-how-to-check-if-an-nsoperation-is-in-an-nsoperationqueue链接。

请参阅ios-nsoperationqueue-operations-all-run-when- added-and-dont-queue链接。

于 2013-01-06T06:36:48.330 回答
0

我会考虑使用 anAFHTTPClient来处理您的下载，特别是因为您想管理多个下载。初始化客户端后，您需要创建所有操作，然后使用方法将它们添加到客户端操作队列中-[AFHTTPClient enqueueBatchOfHTTPRequestOperations: progressBlock: completionBlock:]。这样，您还可以使用进度块确定下载进度。此外，完成块将允许您在完成时执行自己的自定义代码。

因此，您将从初始化客户端开始：

AFHTTPClient *client =[AFHTTPClient clientWithBaseURL:baseURL];

然后你想创建你的 HTTP 请求操作：

NSMutableURLRequest *request = [client requestWithMethod:@"GET" path:@"/" parameters:nil];
AFHTTPRequestOperation *firstOperation = [client HTTPRequestOperationWithRequest:request success:nil failure:nil];
AFHTTPRequestOperation *secondOperation = [client HTTPRequestOperationWithRequest:request success:nil failure:nil];

然后，您只需将这些操作添加到客户端操作队列中：

[client enqueueBatchOfHTTPRequestOperations:@[firstOperation, secondOperation, thirdImageRequestOperation] 
                              progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
                              //Handle progress here
                              } 
                            completionBlock:^(NSArray *operations) {
                             //Handle completion of all downloads here
}];

希望这可以帮助：）

于 2013-07-05T11:09:56.007 回答