swift - UIPageViewController : move programmatically page doesn't work -

i try turn page touching button on 1 of 2 navigation controllers(each navigationcontroller related viewcontroller) when call function in pageviewcontroller change index , change page doesn't work @ all...

i tried setviewcontroller.

i like in snapchat app, navbuttonitem can slide left or right.

thank in advance

here code of pageviewcontroller :

class pageviewcontroller: uipageviewcontroller,uipageviewcontrollerdatasource, uipageviewcontrollerdelegate{      var index = 0     var identifiers: nsarray = ["firstnavigationcontroller", "secondnavigationcontroller"]  override func viewdidload() {      self.datasource = self     self.delegate = self      let startingviewcontroller = self.viewcontrolleratindex(self.index)     let viewcontrollers: nsarray = [startingviewcontroller]     self.setviewcontrollers(viewcontrollers [anyobject], direction: uipageviewcontrollernavigationdirection.forward, animated: false, completion: nil)  }  func viewcontrolleratindex(index: int) -> uinavigationcontroller! {      let storyboard : uistoryboard = uistoryboard(name: "main", bundle:nil)     //first view controller = firstviewcontrollers navigation controller     if index == 0 {          return storyboard.instantiateviewcontrollerwithidentifier("firstnavigationcontroller") uinavigationcontroller      }      //second view controller = secondviewcontroller's navigation controller     if index == 1 {          return storyboard.instantiateviewcontrollerwithidentifier("secondnavigationcontroller") uinavigationcontroller     }      return nil } func pageviewcontroller(pageviewcontroller: uipageviewcontroller, viewcontrollerafterviewcontroller viewcontroller: uiviewcontroller) -> uiviewcontroller? {      let identifier = viewcontroller.restorationidentifier     let index = self.identifiers.indexofobject(identifier!)      //if index end of array, return nil since dont want view controller after last 1     if index == identifiers.count - 1 {          return nil     }      //increment index viewcontroller after current index     self.index = self.index + 1     return self.viewcontrolleratindex(self.index)  }  func pageviewcontroller(pageviewcontroller: uipageviewcontroller, viewcontrollerbeforeviewcontroller viewcontroller: uiviewcontroller) -> uiviewcontroller? {      let identifier = viewcontroller.restorationidentifier     let index = self.identifiers.indexofobject(identifier!)      //if index 0, return nil since dont want view controller before first 1     if index == 0 {          return nil     }      //decrement index viewcontroller before current 1     self.index = self.index - 1     return self.viewcontrolleratindex(self.index)  } } 

first, why don't stop each instance of controllers rather re-instantiating ? here line :

func viewcontrolleratindex(index: int) -> uinavigationcontroller! {  let storyboard : uistoryboard = uistoryboard(name: "main", bundle:nil) //first view controller = firstviewcontrollers navigation controller if index == 0 {      return storyboard.instantiateviewcontrollerwithidentifier("firstnavigationcontroller") uinavigationcontroller  }  //second view controller = secondviewcontroller's navigation controller if index == 1 {      return storyboard.instantiateviewcontrollerwithidentifier("secondnavigationcontroller") uinavigationcontroller }  return nil} 

you create local array containing instances..

then, move programmatically between pages, can use setviewcontroller way :

func showaviewcontroller(){     let startvc : nsarray = [viewcontroller]      setviewcontrollers(startvc as! [anyobject], direction: .reverse, animated: true, completion: nil) } 

where direction .reverse or .forward depending on position of destination view controller relative present view controller.

here example of test program wrote, worked me :

class rootvc: uipageviewcontroller, uipageviewcontrollerdatasource, uipageviewcontrollerdelegate {  var viewcontroller1 : uiviewcontroller! var viewcontroller2 : uiviewcontroller!  override func viewdidload() {     super.viewdidload()     datasource = self      viewcontroller1 = storyboard?.instantiateviewcontrollerwithidentifier("viewcontroller1") as! uiviewcontroller     viewcontroller1.title = "viewcontroller1"      viewcontroller2 = storyboard?.instantiateviewcontrollerwithidentifier("viewcontroller2") as! uiviewcontroller     viewcontroller2.title = "viewcontroller2"      var startingvc : nsarray = [viewcontroller1]     setviewcontrollers(startingvc as! [anyobject], direction: .forward, animated: false, completion: nil)      notifications.addobserver(self, selector: "showviewcontroller1", name: "showviewcontroller1", object: nil)     notifications.addobserver(self, selector: "showviewcontroller2", name: "showviewcontroller2", object: nil) }  deinit{     notifications.removeobserver(self) }  func showviewcontroller1(){     let startvc : nsarray = [viewcontroller1]      setviewcontrollers(startvc as! [anyobject], direction: .forward, animated: true, completion: nil) } func showviewcontroller2(){     let startvc : nsarray = [viewcontroller1]      setviewcontrollers(startvc as! [anyobject], direction: .forward, animated: true, completion: nil) }   func pageviewcontroller(pageviewcontroller: uipageviewcontroller, viewcontrollerbeforeviewcontroller viewcontroller: uiviewcontroller) -> uiviewcontroller? {     switch viewcontroller.title!{         case "viewcontroller1": return nil         case "viewcontroller2": return viewcontroller1     default: return nil     } }  func pageviewcontroller(pageviewcontroller: uipageviewcontroller, viewcontrollerafterviewcontroller viewcontroller: uiviewcontroller) -> uiviewcontroller? {     switch viewcontroller.title!{     case "viewcontroller1": return viewcontroller2     case "viewcontroller2": return viewcontroller1     default: return nil     } }} 

nsnotificationsis not mandatory, use avoid heavy delegation.