SwiftUIからUIPageViewControllerを使用した際に生じる不具合について
SwiftUIでUIPageViewControllerを使用した際に、一度ページをめくると、その後、他のページに移動することができなくなる現象が生じて困っております。
解決方法をご教授いただけると幸いです。
エラーの発生を確認した環境は、Xcode 14.2 iOS15及びiOS16です。
参考にしたサイト→https://www.yururiwork.net/archives/750
問題を再現するコード
import SwiftUI
struct ContentView: View {
@State var page = 1
var body: some View {
VStack{
Text(page.description)
.font(.title)
.bold()
PageView([Text("oo"),Text("kkkk"),Text("jjj")], currentPage: $page)
}
}
}
struct PageView<Page: View>: View {
var viewControllers: [UIHostingController<Page>]
@Binding var currentPage: Int
init(_ views: [Page], currentPage: Binding<Int>) {
self.viewControllers = views.map { UIHostingController(rootView: $0) }
self._currentPage = currentPage
}
var body: some View {
VStack {
PageViewController(controllers: viewControllers, currentPage: $currentPage)
}
}
}
struct PageViewController: UIViewControllerRepresentable {
var controllers: [UIViewController]
@Binding var currentPage: Int
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
func makeUIViewController(context: Context) -> UIPageViewController {
let pageViewController = UIPageViewController(
transitionStyle: .scroll,
navigationOrientation: .horizontal)
pageViewController.dataSource = context.coordinator
pageViewController.delegate = context.coordinator
return pageViewController
}
func updateUIViewController(_ pageViewController: UIPageViewController, context: Context) {
pageViewController.setViewControllers(
[controllers[currentPage]], direction: .forward, animated: true)
}
class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
var parent: PageViewController
init(_ pageViewController: PageViewController) {
self.parent = pageViewController
}
func pageViewController(
_ pageViewController: UIPageViewController,
viewControllerBefore viewController: UIViewController) -> UIViewController?
{
guard let index = parent.controllers.firstIndex(of: viewController) else {
return nil
}
if index == 0 {
return parent.controllers.last
}
return parent.controllers[index - 1]
}
func pageViewController(
_ pageViewController: UIPageViewController,
viewControllerAfter viewController: UIViewController) -> UIViewController?
{
guard let index = parent.controllers.firstIndex(of: viewController) else {
return nil
}
if index + 1 == parent.controllers.count {
return parent.controllers.first
}
return parent.controllers[index + 1]
}
func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
if completed,
let visibleViewController = pageViewController.viewControllers?.first,
let index = parent.controllers.firstIndex(of: visibleViewController)
{
parent.currentPage = index
}
}
}
}
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