Calling parent View Controller function from a subview
<p>I have a parent ViewController with two subview controllers.</p>

<p>When I load the parent view controller it will display two of the subviews. I can also swipe left or right to slide subviews. I now have a requirement to add a button on subviews. On clicking the button it should slide automatically to next subview.</p>

<p>This is what i'm planning -  place a button on subview viewcontroller. Hitting the button will call a function in parent viewcontroller that is responsible for sliding. right now i'm unable to call parent viewcontroller's function. I need the current instance of parent view controller.
Can someone please help?</p>

<p>on the picture, grey is subview viewcontroller 1
green is is subview viewcontroller 2. 
clicking on button of viewcontroller1 should slide to viewcontroller 2</p>

<p><a href="http://i.stack.imgur.com/rgeEv.png" rel="nofollow">Please click here for screen print</a></p>