如何上傳文件到谷歌驅動器，只有當它不存在？

Question

我使用xcode開發iphone應用程序。

我用這段代碼上傳數據庫文件到我的谷歌驅動器。

- (void)uploadDB{ 
    GTLDriveFile *file = [GTLDriveFile object]; 
    file.title = [NSString stringWithFormat:@"User:%@DB.sqlite",UserName]; 
    file.descriptionProperty = @"Uploaded from iOS "; 
    file.mimeType = @"application/x-sqlite3"; 


    // Attach a DB file to the email 

    NSArray *paths = NSSearchPathForDirectoriesInDomains 
    (NSDocumentDirectory, NSUserDomainMask, YES); 

    NSString *documentsDirectory = [paths objectAtIndex:0]; 

    //make a file name to write the data to using the documents directory: 
    NSString *fileName = [NSString stringWithFormat:@"%@/%@", 
          documentsDirectory,DB_File]; 
    NSData *data = [NSData dataWithContentsOfFile:fileName]; 


    GTLUploadParameters *uploadParameters = [GTLUploadParameters uploadParametersWithData:data MIMEType:file.mimeType]; 
    GTLQueryDrive *query = [GTLQueryDrive queryForFilesInsertWithObject:file 
                 uploadParameters:uploadParameters]; 

    UIAlertView *waitIndicator = [self showWaitIndicator:@"Uploading to Google Drive"]; 

    [self.driveService executeQuery:query 
        completionHandler:^(GTLServiceTicket *ticket, 
             GTLDriveFile *insertedFile, NSError *error) { 
         [waitIndicator dismissWithClickedButtonIndex:0 animated:YES]; 
         if (error == nil) 
         { 
          NSLog(@"File ID: %@", insertedFile.identifier); 
          [self showAlert:@"Google Drive" message:@"File saved!"]; 
         } 
         else 
         { 
          NSLog(@"An error occurred: %@", error); 
          [self showAlert:@"Google Drive" message:@"Sorry, an error occurred!"]; 
         } 
        }]; 

} 

我的問題，它總是將其保存爲一個新的文件，我的魔杖，如果這個文件名驅動器存在，並且替換它，它會檢查。

謝謝

Answer 1

驅動器中文件的標題不是唯一的。相反，你應該使用資源ID。您第一次上傳數據庫文件時，請記住它在成功時向您提供的資源ID，然後從此更新。