Programmatically flip UIPageController page from unconventional UIPageController setup - ios

Question

Similar questions to mine have been asked numerous times, however, in my situation I set up the UIPageViewController in an unconventional method. And over the past day and a half of trying to implement the other questions solutions into my program, I have come to believe that they only work with a more conventional method of setting up the UIPageViewController. For some background, I have two UIViewControllers that are being transitioned between in a UIPageViewController. I would like to be able to programmatically change the page of the UIPageViewController from one of the views controllers.
Here is my UIPageViewController class:
class transitionController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
lazy var arrayVC: [UIViewController] = {
return [
self.VCInstance(name: "VC1"),
self.VCInstance(name: "VC2")
]
}()
private func VCInstance(name: String) -> UIViewController {
return UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: name)
}
override func viewDidLoad() {
super.viewDidLoad()
self.dataSource = self
self.delegate = self
if let VC1 = arrayVC.first{
setViewControllers([VC1], direction: .forward, animated: true, completion: nil)
}
}
public func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = arrayVC.index(of: viewController) else{
return nil
}
guard FIRAuth.auth()?.currentUser?.uid != nil else {
return nil
}
let previousIndex = viewControllerIndex - 1
guard previousIndex >= 0 else {
return nil
}
guard arrayVC.count > previousIndex else{
return nil
}
return arrayVC[previousIndex]
}
public func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = arrayVC.index(of: viewController) else{
return nil
}
guard FIRAuth.auth()?.currentUser?.uid != nil else {
return nil
}
let nextIndex = viewControllerIndex + 1
guard nextIndex < arrayVC.count else {
return nil
}
guard arrayVC.count > nextIndex else{
return nil
}
return arrayVC[nextIndex]
}
}
I have tried to flip the pages with this block of code in my VC1:
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "VC2")
transitionController().setViewControllers([vc]?, direction: .Forward, animated: true, completion: nil)
I believe that this doesn't work as I am creating a new instance of the transition controller(I could be wrong).
How can I programmatically flip pages of the UIPageViewController from within the VC1 or VC2 classes using my method of setting up the UIPageViewController?
Thanks in advance.