I'm using a PageViewController from this tutorial

And I would like to pass a function that will run inside the coordinator once the user has reached the final index.

Here is my code:

PageViewController.swift

import SwiftUI
import UIKit

struct PageViewController<Page: View>: UIViewControllerRepresentable {
    var pages: [Page]
    var onLast: () -> Void
    @Binding var currentPage: Int

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    func makeUIViewController(context: Context) -> UIPageViewController {
        let pageViewController = UIPageViewController(
            transitionStyle: .scroll,
            navigationOrientation: .vertical)
        pageViewController.dataSource = context.coordinator
        pageViewController.delegate = context.coordinator

        return pageViewController
    }

    func updateUIViewController(_ pageViewController: UIPageViewController, context: Context) {
        pageViewController.setViewControllers(
            [context.coordinator.controllers[currentPage]], direction: .forward, animated: true)
    }

    class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
        var parent: PageViewController
        var controllers = [UIViewController]()

        init(_ pageViewController: PageViewController) {
            parent = pageViewController
            controllers = parent.pages.map { UIHostingController(rootView: $0) }
        }

        func pageViewController(
            _ pageViewController: UIPageViewController,
            viewControllerBefore viewController: UIViewController) -> UIViewController?
        {
            guard let index = controllers.firstIndex(of: viewController) else {
                return nil
            }
            if index == 0 {
                onLast()
                return controllers.last
            }
            return controllers[index - 1]
        }

        func pageViewController(
            _ pageViewController: UIPageViewController,
            viewControllerAfter viewController: UIViewController) -> UIViewController?
        {
            guard let index = controllers.firstIndex(of: viewController) else {
                return nil
            }
            if index   1 == controllers.count {
                return controllers.first
            }
            return controllers[index   1]
        }

        func pageViewController(
            _ pageViewController: UIPageViewController,
            didFinishAnimating finished: Bool,
            previousViewControllers: [UIViewController],
            transitionCompleted completed: Bool) {
            if completed,
               let visibleViewController = pageViewController.viewControllers?.first,
               let index = controllers.firstIndex(of: visibleViewController) {
                parent.currentPage = index
            }
        }
    }
}


struct PageView<Page: View>: View, Equatable { // << confirm !!
    static func == (lhs: PageView<Page>, rhs: PageView<Page>) -> Bool {
        return true // just for demo, make it meaningful on some property
    }
    var pages: [Page]
    var onLast: () -> Void
    @Binding var currentPage: Int

    var body: some View {
        PageViewController(pages: pages, onLast: onLast, currentPage: $currentPage)
    }
}

struct PageView<Page: View>: View, Equatable { // << confirm !!
    static func == (lhs: PageView<Page>, rhs: PageView<Page>) -> Bool {
        return true // just for demo, make it meaningful on some property
    }
    var pages: [Page]
    var onLast: () -> Void
    @Binding var currentPage: Int

    var body: some View {
        PageViewController(pages: pages, onLast: onLast, currentPage: $currentPage)
    }
}

SwiftUI View

import SwiftUI

struct Test: View {
    @State var color: Color = Color.blue
    
    var body: some View {
        PageView(
            pages: [
                AnyView(
                    color
                ),
                AnyView(
                    Color.purple
                ),
                AnyView(Color.green),
                AnyView(Color.orange),
            ],
             onLast: {
                    color = Color.red
                },
             currentPage: $currentPage
        )
        .equatable()
    }
}

Whenever I try to call onLast() inside the Coordinator, I get the error:

Instance member 'onLast' of type 'PageViewController<Page>' cannot be used on instance of nested type 'PageViewController<Page>.Coordinator'

So not sure how to do this, or if it's possible, I'd appreciate any help or pointers, thank you.

CodePudding user response：

Coordinator is another class (just internal), you have to call it on parent, like

if index == 0 {
    parent.onLast()           // << here !!
    return controllers.last
}