I have 2 problems in my code.
One is compile error [Cannot convert value of type 'Page1' to expected element type '_'] is shown at ★.
Another is that when backward button is pressed, Page2(blue) disappeared while alert sheet is showing. (comment out "Page1(page: self.$page)," and then build source) Expected behavior is that Page2(blue) does not disappear until alert button(Yes) is pressed.
Can anyone tell me how to solve these problems?
import SwiftUI
struct PageViewController: UIViewControllerRepresentable {
var controllers: [UIViewController]
@Binding var currentPage: Int
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
func makeUIViewController(context: Context) -> UIPageViewController {
let pageViewController = UIPageViewController(
transitionStyle: .pageCurl,
navigationOrientation: .vertical)
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 nil
}
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 nil
}
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
}
}
}
}
struct PageView<Page: View>: View {
var viewControllers: [UIHostingController<Page>]
@Binding var currentPage: Int
init(_ views: [Page], currentPage: Binding<Int>) {
self._currentPage = currentPage
self.viewControllers = views.map { UIHostingController(rootView: $0) }
}
var body: some View {
PageViewController(controllers: viewControllers, currentPage: $currentPage)
}
}
struct ContentView: View {
@State var page: Int = 0
var body: some View {
VStack {
PageView([
Page1(page: self.$page), // ★ error
Page2(page: self.$page)// ★ error
], currentPage: $page)
}
}
}
struct Page1: View{
@Binding var page: Int
var body: some View {
ZStack{
Color.red
VStack{
Text("page1")
Button (
action: { self.page += 1 }
){
Image(systemName: "forward")
.accentColor(Color.yellow)
}
}
}
}
}
struct Page2: View{
@State private var showingAlert: Bool = false
@Binding var page: Int
var body: some View {
ZStack{
Color.blue
VStack{
Text("page2")
Button (
action: { self.showingAlert.toggle() }
){
Image(systemName: "backward")
.accentColor(Color.yellow)
}
}
.alert(isPresented: $showingAlert) {
Alert(
title: Text("Confirm"),
message: Text("Back?"),
primaryButton:
.default(Text("Yes"),
action:{ self.page -= 1 }
),
secondaryButton:
.cancel(Text("No"))
)//alert
}//alert
}
}
}
