iphone - IOS Swift - Passing data between view controllers using container view -

i little confused on how use container views correctly, try explain best can.

i have main view controller has animation function.

import uikit  class mainviewcontroller: uiviewcontroller,uipickerviewdatasource,uipickerviewdelegate {  // run view setups override func viewdidload() {     super.viewdidload() }  func closepicker(){     self.view.layoutifneeded();     uiview.animatewithduration(0.5, animations: {             self.countrypickerconst.constant = -206;         self.view.layoutifneeded();     }) }   } 

in interface builder have added container view new view controller contains button so:

import uikit  class containerviewcontroller: uiviewcontroller {  override func viewdidload() {     super.viewdidload()      // additional setup after loading view. }  override func didreceivememorywarning() {     super.didreceivememorywarning()     // dispose of resources can recreated. }    @ibaction func runanimation(sender: uibutton) {      //i want call function in other view controller  }   } 

in action runanimation want call function in mainviewcontroller. if create instance of mainviewcontroller , call function seems loose 'self' relevance.

if explain me best practice doing things great.

thanks

from explanation mainviewcontroller parent of containerviewcontroller access closepicker containerviewcontroller do:

@ibaction func runanimation(sender: uibutton) {   (self.parentviewcontroller as! mainviewcontroller).closepicker() }