IOS：如何使用ios google drive sdk API下载Google Docs文件？
我集成谷歌drivs sdk与我的iOS应用程序。 目前正在使用下面的代码，从我的谷歌驱动器的A / C下载url链接下载文件。 但是，当我尝试下载谷歌文档文件（其中有MIMEtypes的应用程序/ vnd.google-apps.document ）没有从谷歌驱动器库下载URL链接。 在这种情况下，我怎么能下载谷歌文档数据？ 我可以使用alternateLink而不是下载url链接？ 任何帮助，必须感激。
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); } }]; }
这里的步骤从谷歌驱动器下载文件。 它将适用于文件和谷歌文档。
步骤1：
获取文件列表，并将其存储到一个数组或字典与相关的文件下载链接url：
- (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); } }];
}
第2步：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：根据表格行中的文件select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); } }];
Google文档原生格式的文档不能作为其他文件下载，而只能使用exportLinksurl导出为不同的支持格式。
有关更多详情和支持的格式列表，请查看Google Drive SDK文档：
https://developers.google.com/drive/manage-downloads#downloading_google_documents
我以前有类似的问题。 具体来说，我没有find在Google文档中创build的原生文档的downloadurl。 他们是空的。 只有通过DrEdit创build的驱动程序（Drive SDK中的解决scheme）才与downloadUrl相关联。
该解决scheme实际上embedded在GTLDriveFileExportLinks实例中的JSON属性中，该实例返回NSMutableDictionary *。 您可以select通过访问JSONString属性来查看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"]);