Someone recently wants to sell me an iPhone, but the seller does not want to show me anything about it. It's a second-hand phone, and I'm worried about it a little bit. Is there any chance to see the information about the seller from bitcoin hash?
No, that's not possible. Bitcoin is pseudonymous. In all likelihood, you will be sent an address which never had any activity on it before. You can't find any relation between that address and the real world (including activity on the blockchain) until a transaction sending money to that address is published. Even if you knew the person who gave you the address, you wouldn't know for sure whether it belongs to them (but you'd of course assume it because why would they give you an address of a different person or one which belongs to no one). They can prove that it belongs to them but they can't prove that it doesn't and you as someone it doesn't belong to can't proof they own it nor that they don't.