Notification or Delegate

I am stuck somewhere in message passing. Below is my scenario.

Please help me in writing a protocol with the help of which i can communicate between view controllers.

With reference to attached picture my Container view wants to communicate with View controller one, two, three and four but one at a time.

I have implemented notification but it seems to be a bad idea to me.

Please help me in implementing it in a correct way.

Thank you in anticipation Ankush