Getting error with Page View Controller

Question

I keep getting the following error :

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'The number of view controllers provided (0) doesn't match the number required (1) for the requested transition.'

I am not sure what I am doing wrong in my PageViewController that could be causing this error. Also I tried to follow the answer provided here. However, the solution didn't help me because I am not sure which piece of my code could be causing the issue. I am pretty new to Swift, so any help would be greatly appreciated.

Update: I figured out that the setViewController is causing the issue, and it goes away when deleted. However, why would that cause an issue? Thanks!

    var pageViewController: UIPageViewController!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    self.pageViewController = harishStoryboard.instantiateViewControllerWithIdentifier("ViewController1") as! UIPageViewController
    self.pageViewController.dataSource = self
    let allViewControllers = [harishStoryboard.instantiateViewControllerWithIdentifier("ViewController2") as! ViewController2, harishStoryboard.instantiateViewControllerWithIdentifier("ViewController3") as! ViewController3, harishStoryboard.instantiateViewControllerWithIdentifier("ViewController4") as! ViewController4, harishStoryboard.instantiateViewControllerWithIdentifier("ViewController5") as! ViewController5, harishStoryboard.instantiateViewControllerWithIdentifier("ViewController6") as! ViewController6, harishStoryboard.instantiateViewControllerWithIdentifier("ViewController7") as! ViewController7]
    let viewControllers = NSArray(object: allViewControllers)
    self.pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .Forward, animated: false, completion: nil)
    self.addChildViewController(pageViewController)
    self.view.addSubview(self.pageViewController.view)
    self.pageViewController.didMoveToParentViewController(self)
}

You should show your code, it's hard to know what you are doing wrong without knowing what you are doing at all — André Fratelli, Dec 26 '15 at 03:25

score 6 · Accepted Answer · answered Dec 26 '15 at 10:35

6

This is not how the page view controller works. You do not pass multiple view controller but only one, or max two. See the apple docs:

When defining a page view controller interface, you can provide the content view controllers one at a time (or two at a time, depending upon the spine position and double-sided state) or as-needed using a data source. When providing content view controllers one at a time, you use the setViewControllers:direction:animated:completion: method to set the current content view controllers. To support gesture-based navigation, you must provide your view controllers using a data source object.

I assume you want gesture bases navigation, so you will need to implement the page view controller delegate and data source. There are plenty of page view controller tutorials on google.

answered Dec 26 '15 at 10:35

Darko

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So does that mean when using the `setViewControllers` method I only provide one view controller? So for example it would be `self.pageViewController.setViewControllers(viewController as? [UIViewController], direction: .Forward, animated: true, completion: nil).` – Harish Dec 26 '15 at 16:04
1

Yes. And the other ViewController are provided over the implementation of the data source. You just pass the first visible one with setViewController. – Darko Dec 26 '15 at 16:17
1

Okay. I set the updated my code. I think that was probably the issue. Thanks for your help. – Harish Dec 26 '15 at 16:41
The only reason you might pass two ViewControllers in an array (to `setViewControllers`) is if you were showing two pages at a time in your `UIPageViewController`. If you're showing one page at a time, then you only pass `setViewControllers` one `UIViewController` at a time, even though you're passing it in an array. – JaredH Feb 22 '18 at 20:28

score 1 · Answer 2 · answered Oct 22 '18 at 19:46

The method set setViewControllers expects just the first view controller to be displayed! Try like this:

if let firstVC = myViewControllers?.first {
    setViewControllers([firstVC], direction: .forward, animated: true)
}

myViewControllers is a property of my UIPageViewController subclass!

Hope it works for you!

Getting error with Page View Controller

2 Answers2