PHAssetCreationRequest DNG File Name

This is a snippet from Apple's sample code AVCamManualExtendingAVCamtoUseManualCaptureAPI where the DNG data has to be temprorily written in to a file:

[PHPhotoLibrary requestAuthorization:^( PHAuthorizationStatus status ) {
  if ( status == PHAuthorizationStatusAuthorized ) {

  NSURL *temporaryDNGFileURL;
  if ( self.dngPhotoData ) {
  temporaryDNGFileURL = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"%lld.dng", resolvedSettings.uniqueID]]];
  [self.dngPhotoData writeToURL:temporaryDNGFileURL atomically:YES];
  }

  [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
  PHAssetCreationRequest *creationRequest = [PHAssetCreationRequest creationRequestForAsset];

  if ( self.jpegPhotoData ) {
  [creationRequest addResourceWithType:PHAssetResourceTypePhoto data:self.jpegPhotoData options:nil];

  if ( temporaryDNGFileURL ) {
  PHAssetResourceCreationOptions *companionDNGResourceOptions = [[PHAssetResourceCreationOptions alloc] init];
  companionDNGResourceOptions.shouldMoveFile = YES;
  [creationRequest addResourceWithType:PHAssetResourceTypeAlternatePhoto fileURL:temporaryDNGFileURL options:companionDNGResourceOptions];
  }
  }
  else {
  PHAssetResourceCreationOptions *dngResourceOptions = [[PHAssetResourceCreationOptions alloc] init];
  dngResourceOptions.shouldMoveFile = YES;
  [creationRequest addResourceWithType:PHAssetResourceTypePhoto fileURL:temporaryDNGFileURL options:dngResourceOptions];
  }

  } completionHandler:^( BOOL success, NSError * _Nullable error ) {
  if ( ! success ) {
  NSLog( @"Error occurred while saving photo to photo library: %@", error );
  }

  if ( [[NSFileManager defaultManager] fileExistsAtPath:temporaryDNGFileURL.path] ) {
  [[NSFileManager defaultManager] removeItemAtURL:temporaryDNGFileURL error:nil];
  }

  [self didFinish];
  }];
  }
  else {
  NSLog( @"Not authorized to save photo" );
  [self didFinish];
  }
  }];

In above code, the line creates the DNG file name using resolvedSettings.uniqueID:

  temporaryDNGFileURL = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"%lld.dng", resolvedSettings.uniqueID]]];

Above line creates a file named, for example, 23lld.dng. This becomes a problem when users want consecutive file names along with JPEG's and other asset file names in the photo library.

If the users last asset's file name is IMG_0155.jpg, the DNG file being created should be IMG_0156.dng in this case.

How would I be able to get the proper name for the DNG file?