Teamwork IOS Developer interview questions

1st interview with HR then a code challenge for 8-12 hours. I'm really disappointed with this process. I spent 12 hours spread in some days and it seems the guy evaluating it didn't spend much. I got a really vague answer and they didn't even want to talk about it first, before rejecting me. I am pretty confident I sent a great code and a good app but I was rejected like I sent a stupid code. it was 12 hours I spent (the maximum suggested) and it wasn't continuous, I had to take a lot of breaks. What are they expecting anyway... I suggest you asked a lot of questions before starting this code, like, what structure are you expecting for the code, because when they say "it's up to you" that won't hellp, because they're not open minded to be flexible to each candidate, it seems the developer that evaluates us is expecting a person exactly like him...