I don't know how exactly use this API to update file content since I didn't get detail information from Document and DriveSample application. Thus, I tried to write it like:

```
GTLRUploadParameters *uploadParameters = [GTLRUploadParameters
                    uploadParametersWithData:data
                                    MIMEType:@"binary/octet-stream"];
GTLRDriveQuery_FilesUpdate *query = [GTLRDriveQuery_FilesUpdate
                                 queryWithObject:cloudPreference
                                          fileId:cloudPreference.identifier
                                uploadParameters:uploadParameters];

[self.driveService executeQuery:query
              completionHandler:^(GTLRServiceTicket *callbackTicket,
                                  GTLRDrive_File *uploadedFile,
                                  NSError *callbackError) {
                  if (callbackError == nil) {
                      NSLog(@"Updating file is finished!");
                  }
                  else {
                      NSLog(@"Failed to update file: %@", callbackError);
                  }
              }];

```

The error is:
**Failed to update file: Error Domain=com.google.HTTPStatus Code=403 "(null)" UserInfo={data=<7b226572 726f7222 3a7b2265 72726f72 73223a5b ...**

Actually data is JSON format, I tried MIMEType with "applicaton/json" but still got 403 error. I can't google anything about this API with such error. The file is created by my application and I can download data from Google drive in my application. But I don't know what's wrong with my updating codes, Could anyone help me?
Thanks a lot!