如何在SwiftUI中实现PageView？

Question

我是SwiftUI的新手。我有三个视图，我希望它们在PageView中。我想像滑动浏览器一样滑动每个“视图”，并希望这些小点表示我所在的视图。

Answer 1

页面控制

struct PageControl: UIViewRepresentable {
    var numberOfPages: Int
    @Binding var currentPage: Int
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    func makeUIView(context: Context) -> UIPageControl {
        let control = UIPageControl()
        control.numberOfPages = numberOfPages
        control.pageIndicatorTintColor = UIColor.lightGray
        control.currentPageIndicatorTintColor = UIColor.darkGray
        control.addTarget(
            context.coordinator,
            action: #selector(Coordinator.updateCurrentPage(sender:)),
            for: .valueChanged)

        return control
    }

    func updateUIView(_ uiView: UIPageControl, context: Context) {
        uiView.currentPage = currentPage
    }

    class Coordinator: NSObject {
        var control: PageControl

        init(_ control: PageControl) {
            self.control = control
        }
        @objc
        func updateCurrentPage(sender: UIPageControl) {
            control.currentPage = sender.currentPage
        }
    }
}

您的页面浏览量

struct PageView<Page: View>: View {
    var viewControllers: [UIHostingController<Page>]
    @State var currentPage = 0
    init(_ views: [Page]) {
        self.viewControllers = views.map { UIHostingController(rootView: $0) }
    }

    var body: some View {
        ZStack(alignment: .bottom) {
            PageViewController(controllers: viewControllers, currentPage: $currentPage)
            PageControl(numberOfPages: viewControllers.count, currentPage: $currentPage)
        }
    }
}

您的页面视图控制器

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
            }
        }
    }
}

假设您有一个类似的观点

struct CardView: View {
    var album: Album
    var body: some View {
        URLImage(URL(string: album.albumArtWork)!)
            .resizable()
            .aspectRatio(3 / 2, contentMode: .fit)
    }
}

您可以像这样在主swiftUI视图中使用此组件。

 PageView(vM.Albums.map { CardView(album: $0) }).frame(height: 250)