How to check empty records in Core Data?

I'm working on a way to know if data has been downloaded and recorded correctly on Core Data.  Due to the poor quality of 3G connections and the potential for failure, I would like to know if there is a way to query the core data and see if there is any way to return the empty records in an array.

The initial idea I had is to get the records in the entities and scan them for fields with NULL values. And then create a request to populate the data correctly.

But I would like to know if Core Data has a method or function that does this, returning an array with the failed records.

Example Entity with fields filled in failed:

 ID | NOME  | VALOR | IMAGEM 
-------------------------------
  0 | arroz | NULL  | skms.png
-------------------------------
  1 | feijao| NULL  | ksle.png
-------------------------------
  2 | carne | 5,00  | NULL
-------------------------------
  3 | uva   | 6,00  | NULL
-------------------------------
  4 | pera  | 7,00  | lskx.png
-------------------------------
  5 | NULL  | NULL  | NULL
-------------------------------



// Codigo usado para Download
AFHTTPRequestOperationManager *operationManager = [AFHTTPRequestOperationManager manager];
    operationManager.responseSerializer = [AFJSONResponseSerializer serializer];
    [operationManager.requestSerializer setValue:urlGlobalToken forHTTPHeaderField:urlGlobalHttpHeader];

    [operationManager GET:url parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {

        NSMutableArray* arrayDataReceived =  [responseObject objectForKey:@"data"];

        cleanArray = [[NSMutableArray alloc]init];
        arrayURLImagens = [[NSMutableArray alloc]init];

    for ( NSMutableDictionary* valuesDict in arrayDataReceived) {

        // Este modelo é somente para exemplo.
        // This model is only for example.

        NSMutableDictionary* cleanDict = [[NSMutableDictionary alloc]init];

        [cleanDict setObject: [valuesDict objectForKey:@"id"]         forKey:@"id"];
        [cleanDict setObject: [valuesDict objectForKey:@"nome"]       forKey:@"nome"];
        [cleanDict setObject: [valuesDict objectForKey:@"data"]       forKey:@"data"];
        [cleanDict setObject: [valuesDict objectForKey:@"descricao"]  forKey:@"descricao"];
        [cleanDict setObject: [valuesDict objectForKey:@"updated_at"] forKey:@"updateat"];

        // Imagens para update
        [cleanDict setObject: [valuesDict objectForKey:@"imagem"]forKey:@"urlimagem"];
    // Armazena os dicionarios em um Array
    [cleanArray addObject:cleanDict];
}  
    _dadosBrutosRecebidos = [[NSMutableDictionary alloc]init];
    [_dadosBrutosRecebidos setObject:arrayURLImagens forKey:@"urlimagem"];
    [_dadosBrutosRecebidos setObject:cleanArray forKey:@"strings"];

    [self.delegate performSelector:@selector(downloadDadosEventosCompleto)];

     app.networkActivityIndicatorVisible = NO;

} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    app.networkActivityIndicatorVisible = NO;
    NSLog(@"failure. Error:%@. URL ERRO: %@",error, url);
  }];
}