title: How to replace content ViewController inside other View controller
body: <p>I am working on an application which allows users to work with a couple of workmodes. Main view of the app contains information common to all workmodes. I want to create a &quot;subview&quot; with ability to change its ViewController. This subview will be used to display information connected with specified workmode. It is important that app goes to MainViewController from WorkmodesViewController in which user chooses workmode to work with.</p>
  <p>My question is:
  Which tehnique should I use to acheave changeable WorkmodeViewController inside MainViewVontroller</p>
  <p><img src="https://i.stack.imgur.com/LYWJa.png" alt="enter image description here" /></p>