In a chat 1:1 (being it the native QB chat 1:1 feature or a Chat room for 2 users), how can I let a user know that his opponent is typing? Is it even posible with Quickblox?
Yes, it's possible. It's called Chat State Notifications
Here is a guide how to do this in 1-1 Chat
http://quickblox.com/developers/SimpleSample-chat_users-ios#Chat_State_Notifications