how to get all files in pdf format can dropbox convert before i download it through the API

        NSString * authorizToken = @"Bearer <Acess Token>";

        NSURL *url = [NSURL URLWithString:[[NSString stringWithFormat:@"https://content.dropboxapi.com/1/previews/auto/%@",dropboxPath ] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]  ];

        NSMutableURLRequest *request =

        [NSMutableURLRequest requestWithURL:url

                                cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData

                            timeoutInterval:10

         ];

        [request setValue:authorizToken forHTTPHeaderField:@"Authorization"];

        [request setHTTPMethod: @"GET"];

        NSError *requestError = nil;

        NSURLResponse *urlResponse = nil;

        NSData *response1 =

        [NSURLConnection sendSynchronousRequest:request

                              returningResponse:&urlResponse error:&requestError];

        [response1 writeToFile:pdfPath atomically:YES];


Error fie not found

when i do this

      [pMainDelegate.restClient searchPath:@" forKeyword:dropboxData.fileName];
it returns that file exits and in the rest client there is no method which helps me in call the https://content.dropboxapi.com/1/previews/auto