Eurobubba

Eurobubba

SwiftUI class notes 2021-11-28

Apple tutorial: Interfacing with UIKit

Completely lost on this coordinator stuff.

import SwiftUI
import UIKit

struct PageViewController<Page: View>: UIViewControllerRepresentable {
    var pages: [Page]
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    func makeUIViewController(context: Context) -> UIPageViewController {
        let pageViewController = UIPageViewController(
            transitionStyle: .scroll,
            navigationOrientation: .horizontal
        )
        pageViewController.dataSource = context.coordinator
        
        return pageViewController
    }
    
    func updateUIViewController(_ pageViewController: UIPageViewController, context: Context) {
        pageViewController.setViewControllers([context.coordinator.controllers[0]], direction: .forward, animated: true)
    }
    
    class Coordinator: NSObject, UIPageViewControllerDataSource {
        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 {
                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]
        }
    }
}