(Swift) how can I change view in pageviewcontroller with touching button - ios

Question

I'm using PageViewController and tab bar. And I have a question which is 'how to move another view by touching button.' My app has 5 ViewControllers and they are on PageViewController. And the PageViewController is on ViewController. That ViewController is MainController. So I separated Main view, with about 4 : 1(PageViewController : tab bar). So tab bar is on MainController, MainController can changes ViewController when tab item is touched.
But what I want to make is a button on one of five ViewControllers which can change ViewController.
The button has not right to change ViewController. So I searched how to solve this problem but It couldn't find good solution.
I think the solution is very short, about 1 ~ 2 sentences.
I attached my code, so I hope anybody who know how to solve this problem please helps me.
I'm new in Swift, so explain detail please
This is a part of MainController
import UIKit
class ViewController: UIViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
var pageViewController: UIPageViewController!
var subVC: [UIViewController] = []
var viewIndex: Int = 0
var tabIndicator1 = UIView()
var tabIndicator2 = UIView()
var tabIndicator3 = UIView()
var tabIndicator4 = UIView()
var tabIndicator5 = UIView()
var views = [UIView]()
override func viewDidLoad() {
super.viewDidLoad()
createVC() // make five ViewControllers
self.pageViewController = self.storyboard?.instantiateViewController(withIdentifier: "PageViewController") as! UIPageViewController
self.pageViewController = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
self.pageViewController.view.frame = CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height)
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
let startVC = subVC[0]
viewIndex = 0
let viewControllers = NSArray(object: startVC)
self.pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .forward, animated: true, completion: nil)
self.pageViewController.didMove(toParentViewController: self)
createTabBar() // make Tab Bar
createIndicator() // make Tab Indicator
self.pageViewController.dataSource = self
self.pageViewController.delegate = self
}
...
func createVC() { // I have five ViewController files
let HomeVC = VCInstance(name: "Home")
let AccessVC = VCInstance(name: "AccessLog")
let RegisterVC = VCInstance(name: "Register")
let SettingVC = VCInstance(name: "Setting")
let HelpVC = VCInstance(name: "Help")
subVC = [HomeVC, AccessVC, RegisterVC, SettingVC, HelpVC]
}
func VCInstance(name: String) -> UIViewController {
return UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: name)
}
....

Answer 1

You can use this code it might be help you.
extension UIViewController {
func goNextPage(animated: Bool = true) {
guard let currentViewController = self.viewControllers?.first else { return }
guard let nextViewController = dataSource?.pageViewController(self, viewControllerAfter: currentViewController) else { return }
setViewControllers([nextViewController], direction: .forward, animated: animated, completion: nil)
}
func goPreviousPage(animated: Bool = true) {
guard let currentViewController = self.viewControllers?.first else { return }
guard let previousViewController = dataSource?.pageViewController(self, viewControllerBefore: currentViewController) else { return }
setViewControllers([previousViewController], direction: .reverse, animated: animated, completion: nil)
}
}