Can't Download File From Dropbox downloadData With Objective-C

Hello,

I am trying to use the following code to download data from Dropbox using the Vs2 API:

NSString *filePath = @"/joelLockFolderV2_1489675832.409768.tsl";

[[client.filesRoutes downloadData:filePath]
    setResponseBlock:^(DBFILESFileMetadata *result, DBFILESDownloadError *routeError, DBRequestError *error,
                       NSData *fileContents) {
      if (result) {
        NSLog(@"%@\n", result);
        NSString *dataStr = [[NSString alloc] initWithData:fileContents encoding:NSUTF8StringEncoding];
        NSLog(@"%@\n", dataStr);
      } else {
        NSLog(@"%@\n%@\n", routeError, error);
      }
    }];

When I try this I receive the following error:

2017-03-16 15:58:35.759 xctest[78431:5712864] (null)
DropboxClientError[{
    NSError = "Error Domain=NSURLErrorDomain Code=-1 \"unknown error\" UserInfo={NSErrorFailingURLKey=https://api-content.dropbox.com/2/files/download, NSLocalizedDescription=unknown error, NSErrorFailingURLStringKey=https://api-content.dropbox.com/2/files/download}";
}];

I have checked and the file at filePath exists. I've found that various Api calls correctly work. I am having the same problem with 

[client.filesRoutes downloadUrl:filePath overwrite:TRUE destination:ril]

And:

[[client.filesRoutes uploadUrl:remoteFilePath inputUrl:localURL]

I've tried setting 'NSAppTransportSecurity' to Allow Arbitary loads.

Is there anything I am missing...?

Regards,

Joel