UIPageViewController : move programmatically page doesn't work - swift

Question

I try to turn the page by touching a button on one of the two navigation controllers(each navigationcontroller is related to a viewcontroller) but when i call a function in the pageviewcontroller to change index and change page it doesn't work at all...
I tried setViewController.
I would like to do like in the snapchat app, a navbuttonitem which can slide to the left or to the right.
Thank you in advance
here is the code of the 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 as [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") as UINavigationController
}
//second view controller = secondViewController's navigation controller
if index == 1 {
return storyBoard.instantiateViewControllerWithIdentifier("SecondNavigationController") as UINavigationController
}
return nil
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
let identifier = viewController.restorationIdentifier
let index = self.identifiers.indexOfObject(identifier!)
//if the index is the end of the array, return nil since we dont want a view controller after the last one
if index == identifiers.count - 1 {
return nil
}
//increment the index to get the viewController after the 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 the index is 0, return nil since we dont want a view controller before the first one
if index == 0 {
return nil
}
//decrement the index to get the viewController before the current one
self.index = self.index - 1
return self.viewControllerAtIndex(self.index)
}
}

Answer 1

First, why don't you stop each instance of your controllers rather than re-instantiating it ? Here is the 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") as UINavigationController
}
//second view controller = secondViewController's navigation controller
if index == 1 {
return storyBoard.instantiateViewControllerWithIdentifier("SecondNavigationController") as UINavigationController
}
return nil}
You could create a local array containing all your instances..
Then, to move programmatically between your pages, you can use setViewController this way :
func showAViewController(){
let startVC : NSArray = [viewController]
setViewControllers(startVC as! [AnyObject], direction: .Reverse, animated: true, completion: nil)
}
Where direction is .Reverse or .Forward depending on the position of the destination view controller relative to the present view controller.
Here is an example of a test program I wrote, it worked for 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 a mandatory, but I like to use it to avoid heavy delegation.