IOS：如何使用IOS Google drive sdk API下载Google文档文件？

我将google drivs sdk与我的ios应用程序集成。目前，我使用以下代码从我的谷歌硬盘a/c下载基于下载url链接的文件。但是，当我试图下载google文档文件（其mime类型为application/vnd.google apps.document）时，google drive库中没有下载url链接。在这种情况下，我如何下载谷歌文档数据？。我可以使用alternateLink代替下载url链接吗？。任何帮助都必须感谢

我的代码：

- (void)loadFileContent {

GTMHTTPFetcher *fetcher =
[self.driveService.fetcherService fetcherWithURLString:[[self.driveFiles objectAtIndex:selectedFileIdx] downloadUrl]];

[fetcher beginFetchWithCompletionHandler:^(NSData *data, NSError *error) {
    if (error == nil) {
        NSLog(@"\nfile %@ downloaded successfully from google drive", [[self.driveFiles objectAtIndex:selectedFileIdx] originalFilename]);

        //saving the downloaded data into temporary location

    } else {
        NSLog(@"An error occurred: %@", error);            

    }
}];

---

}

谷歌文档本机格式的文档不能作为其他文件下载，只能使用

exportLinks

URL导出为不同的支持格式

有关更多详细信息和支持的格式列表，请查看Google Drive SDK文档：

---

我以前也有过类似的问题。具体来说，我没有找到在Google文档中创建的本机文档的下载URL。它们是空的。只有通过DrEdit（驱动器SDK中举例说明的解决方案）创建的内容与下载URL关联

该解决方案实际上嵌入在GTLDriveFileExportLinks实例中的属性：JSON中，该实例返回NSMutableDictionary*。您可以选择通过access JSONString属性查看JSON对象的内容。可以通过查询GTLDriveFile实例中的exportLinks来获取JSON可变字典。示例如下：

GTLDriveFile *file = files.items[0]; // assume file is assigned to a valid instance.
NSMutableDictionary *jsonDict = file.exportLinks.JSON; 
NSLog(@"URL:%@.", [jsonDict objectForKey:@"text/plain"]);

---

下面是从google drive下载文件的步骤。它既适用于文件，也适用于谷歌文档

步骤1：

获取文件列表并使用相关文件下载链接url将其存储到数组或dict中：

- (void)loadDriveFiles {
fileFetchStatusFailure = NO;

//for more info about fetching the files check this link
//https://developers.google.com/drive/v2/reference/children/list    
GTLQueryDrive *query2 = [GTLQueryDrive queryForChildrenListWithFolderId:[parentIdList lastObject]];
query2.maxResults = 1000;

// queryTicket can be used to track the status of the request.
[self.driveService executeQuery:query2
              completionHandler:^(GTLServiceTicket *ticket,
                                  GTLDriveChildList *children, NSError *error) {
                  GTLBatchQuery *batchQuery = [GTLBatchQuery batchQuery];                      
                  //incase there is no files under this folder then we can avoid the fetching process
                  if (!children.items.count) {                          
                      [self.driveFiles removeAllObjects];
                      [fileNames removeAllObjects];                          
                      [self performSelectorOnMainThread:@selector(reloadTableDataFromMainThread) withObject:nil waitUntilDone:NO];                          
                      return ;
                  }

                  if (error == nil) {
                      int totalChildren = children.items.count;
                      count = 0;

                      [self.driveFiles removeAllObjects];
                      [fileNames removeAllObjects];                                                    //http://stackoverflow.com/questions/14603432/listing-all-files-from-specified-folders-in-google-drive-through-ios-google-driv/14610713#14610713
                      for (GTLDriveChildReference *child in children) {
                          GTLQuery *query = [GTLQueryDrive queryForFilesGetWithFileId:child.identifier];                              
                          query.completionBlock = ^(GTLServiceTicket *ticket, GTLDriveFile *file, NSError *error) {

                              //increment count inside this call is very important. Becasue the execute query call is asynchronous
                              count ++;
                              NSLog(@"Google Drive: retrieving children info: %d", count);                                  
                              if (error == nil) {
                                  if (file != nil) { //checking the file resource is available or not
                                      //only add the file info if that file was not in trash
                                      if (file.labels.trashed.intValue != 1 )
                                          [self addFileMetaDataInfo:file numberOfChilderns:totalChildren];
                                  }

                                  //the process passed all the files then we need to sort the retrieved files
                                  if (count == totalChildren) {
                                      NSLog(@"Google Drive: processed all children, now stopping HUDView - 1");
                                      [self performSelectorOnMainThread:@selector(reloadTableDataFromMainThread) withObject:nil waitUntilDone:NO];
                                  }
                              } else {
                                  //the file resource was not found
                                  NSLog(@"Google Drive: error occurred while retrieving file info: %@", error);

                                  if (count == totalChildren) {
                                      NSLog(@"Google Drive: processed all children, now stopping HUDView - 2");
                                      [self performSelectorOnMainThread:@selector(reloadTableDataFromMainThread)
                                                             withObject:nil waitUntilDone:NO];
                                  }                                      
                              }                                  
                          };                              
                          //add the query into batch query. Since we no need to iterate the google server for each child.
                          [batchQuery addQuery:query];
                      }                          
                      //finally execute the batch query. Since the file retrieve process is much faster because it will get all file metadata info at once
                      [self.driveService executeQuery:batchQuery
                                    completionHandler:^(GTLServiceTicket *ticket,
                                                        GTLDriveFile *file,
                                                        NSError *error) {
                                    }];

                      NSLog(@"\nGoogle Drive: file count in the folder: %d", children.items.count);
                  } else {
                      NSLog(@"Google Drive: error occurred while retrieving children list from parent folder: %@", error);
                  }
              }];

}

步骤2： 添加文件元数据信息

    -(void)addFileMetaDataInfo:(GTLDriveFile*)file numberOfChilderns:(int)totalChildren
{
    NSString *fileName = @"";
    NSString *downloadURL = @"";

    BOOL isFolder = NO;

    if (file.originalFilename.length)
        fileName = file.originalFilename;
    else
        fileName = file.title;

    if ([file.mimeType isEqualToString:@"application/vnd.google-apps.folder"]) {
        isFolder = YES;
    } else {
        //the file download url not exists for native google docs. Sicne we can set the import file mime type
        //here we set the mime as pdf. Since we can download the file content in the form of pdf
        if (!file.downloadUrl) {
            GTLDriveFileExportLinks *fileExportLinks;

            NSString    *exportFormat = @"application/pdf";

            fileExportLinks = [file exportLinks];
            downloadURL = [fileExportLinks JSONValueForKey:exportFormat];
        } else {
            downloadURL = file.downloadUrl;
        }
    }

    if (![fileNames containsObject:fileName]) {
        [fileNames addObject:fileName];

        NSArray *fileInfoArray = [NSArray arrayWithObjects:file.identifier, file.mimeType, downloadURL,
                                  [NSNumber numberWithBool:isFolder], nil];
        NSDictionary *dict = [NSDictionary dictionaryWithObject:fileInfoArray forKey:fileName];

        [self.driveFiles addObject:dict];
    }
}

步骤3： 根据表格行上的文件选择下载文件

    NSString *downloadUrl = [[[[self.driveFiles objectAtIndex:selectedFileIdx] allValues] objectAtIndex:0]
                   objectAtIndex:download_url_link];
NSLog(@"\n\ngoogle drive file download url link = %@", downloadUrl);    
GTMHTTPFetcher *fetcher =
[self.driveService.fetcherService fetcherWithURLString:downloadUrl];    
//async call to download the file data
[fetcher beginFetchWithCompletionHandler:^(NSData *data, NSError *error) {
    if (error == nil) {
        NSLog(@"\nfile %@ downloaded successfully from google drive", self.selectedFileName);

        //saving the downloaded data into temporary location
        [data writeToFile:<path> atomically:YES];               
    } else {
        NSLog(@"An error occurred: %@", error);
    }
}];

NSString*downloadUrl=[[[self.driveFiles objectAtIndex:selectedFileIdx]allValues]objectAtIndex:0]
objectAtIndex:下载\u url\u链接]；
NSLog（@“\n\n日志驱动器文件下载url链接=%@”，下载url）；
GTMHTTPFetcher*取数器=
[self.driveService.fetcherService fetcherWithURLString:downloadUrl]；
//异步调用以下载文件数据
[fetcher beginFetchWithCompletionHandler:^（NSData*数据，NSError*错误）{
如果（错误==nil）{
NSLog（@“\n文件%@已从google drive成功下载”，self.selectedFileName）；
//将下载的数据保存到临时位置
[数据写入文件：原子：是]；
}否则{
NSLog（@“发生错误：%@”，错误）；
}
}];

我查看了文档。但是在那里，我找不到任何与Objectice-C相关的示例。因此，您能告诉我如何从GTLDriveFileExportLinks类中获取导出类型应用程序/pdf。的Objective-C示例演示了如何下载或导出文件您是否设法下载了这些文件？我想知道你是怎么做到的。我也在尝试下载这些文件，但到目前为止，我找不到任何可以帮助我的资源。@Shailesh，是的，我可以从google drive下载这些文件。在我的例子中，当用户点击文件名时，我启动了下载操作。你面临的问题是什么？我使用的是谷歌提供的一个样本代码。项目名称为“DriveSample”，我得到的导出/下载URL为空。下载完全失败。这是我用作参考的URL--@Shailesh，我刚刚在下面发布了我的代码，你可以查看。通常，在获取文件列表信息的同时，谷歌也会为您提供下载url链接，这与本机谷歌文档和您的附件不同。当您知道下载url链接后，您可以使用该url启动下载操作。谢谢！成功了。：）虽然我觉得，谷歌需要开发他们的API文档。在我们的项目中，它的实现方式很复杂。另一方面，Dropbox和SkyDrive有简单而直接的过程。@Shailesh，太棒了！！！：-）是的，你是对的：-）当我开始集成谷歌硬盘时，我遇到了很多问题。@loganathan如果数据超过1GB，这个应用程序会崩溃吗？@MatrosovAlexander，我不确定。我没有检查此用户案例路径。请帮助mi如何在UI中下载按钮单击