present walkthrough scenes only once ios swift - ios

Question

I created a PageViewController and added three view controllers as a walkthrough for my app, but i want them to be displayed only once, and i can't figure out how.
here is my code for the pageViewController:
import UIKit
class MyPageViewController: UIPageViewController{
override func viewDidLoad() {
super.viewDidLoad()
dataSource = self
// Do any additional setup after loading the view.
if let firstViewController = orderedViewControllers.first {
setViewControllers([firstViewController],
direction: .Forward,
animated: true,
completion: nil)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//array for the ordered view controllers
private(set) lazy var orderedViewControllers: [UIViewController] = {
return [self.newColoredViewController("First"),
self.newColoredViewController("Second"),
self.newColoredViewController("Third")]
}()
private func newColoredViewController(color: String) -> UIViewController {
return UIStoryboard(name: "Main", bundle: nil) .
instantiateViewControllerWithIdentifier("\(color)ViewController")
}
}
extension MyPageViewController: UIPageViewControllerDataSource {
//returning index of previous view controller
func pageViewController(pageViewController: UIPageViewController,
viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
return nil
}
let previousIndex = viewControllerIndex - 1
guard previousIndex >= 0 else {
return nil
}
guard orderedViewControllers.count > previousIndex else {
return nil
}
return orderedViewControllers[previousIndex]
}
//returning index of the next view controller
func pageViewController(pageViewController: UIPageViewController,
viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
return nil
}
let nextIndex = viewControllerIndex + 1
let orderedViewControllersCount = orderedViewControllers.count
guard orderedViewControllersCount != nextIndex else {
return nil
}
guard orderedViewControllersCount > nextIndex else {
return nil
}
return orderedViewControllers[nextIndex]
}
}
how do i edit the code to display it only once?

Answer 1

From what you've said I'm guessing that you only want it to show the first time the user opens the app and then not appear again?
Theres a few ways of doing this, the simplest would likely be to set a property on NSUserDefaults, this will remember the setting in between app launches. try something like:
// this should be your initial view controller
let defaults = NSUserDefaults.standardUserDefaults()
override func viewDidLoad() {
super.viewDidLoad()
if !defaults.boolForKey("walkthroughSeen") {
// create page view controller and display
let walkthroughVC = UIStoryboard(name: "Main", bundle: nil).
instantiateViewControllerWithIdentifier("MyPageViewController")
self.presentViewController(walkthroughVC, animated: true)
defaults.setBool(true, forKey: "walkthroughSeen")
}
}