我正在创建一个需要包含数百个页面的 slider 的 SwiftUI 应用程序。由于没有适合我需求的第一方解决方案,我已经适配了UIPageViewController
。主要用例: slider 应允许点击其内容,这将(取消)隐藏导航栏。隐藏单独使用时效果很好,但当我在导航栏隐藏时滑动时,它会重新出现。
如何根据navigationBarHidden(hidden)
隐藏导航栏?
一步一步:
- 点击隐藏(导航栏现在隐藏)
- 滑动(仍然隐藏)
- 滑动(出现)
在大多数情况下,需要滑动两次才能取消隐藏栏,但有时只需滑动一次即可取消隐藏。
这是应用程序的 SwiftUI 部分:
struct ApplicationView: View {
var body: some View {
NavigationView {
ContentView()
.navigationBarTitle(Text("Test"), displayMode: .inline)
}
}
}
struct ContentView: View {
@State private var hidden = false
@State private var currentPage = 0
var body: some View {
PagerView(0..<100, currentPage: $currentPage) {
Text("\($0)")
.frame(maxWidth: .infinity, maxHeight: .infinity)
.onTapGesture { hidden.toggle() }
}
.navigationBarHidden(hidden)
.ignoresSafeArea()
.background(Color.red.ignoresSafeArea())
}
}
和改编的UIPageViewController
:
struct PagerView<Data: RandomAccessCollection, Page: View>: UIViewControllerRepresentable {
private let data: Data
@Binding var currentPage: Data.Index
private let interPageSpacing: CGFloat
private let content: (Data.Element) -> Page
init(
_ data: Data,
currentPage: Binding<Data.Index>,
interPageSpacing: CGFloat = 0,
@ViewBuilder content: @escaping (Data.Element) -> Page
) {
self.data = data
self._currentPage = currentPage
self.interPageSpacing = interPageSpacing
self.content = content
}
func makeUIViewController(context: Context) -> UIPageViewController {
let pageViewController = UIPageViewController(
transitionStyle: .scroll,
navigationOrientation: .horizontal,
options: [.interPageSpacing: interPageSpacing]
)
pageViewController.delegate = context.coordinator
pageViewController.dataSource = context.coordinator
return pageViewController
}
func updateUIViewController(_ uiViewController: UIPageViewController, context: Context) {
let direction: UIPageViewController.NavigationDirection
if let previousViewController = uiViewController.viewControllers?.first as? PageViewController<Page> {
guard previousViewController.index != currentPage else { return }
direction = previousViewController.index < currentPage ? .forward : .reverse
} else {
direction = .forward
}
let page = context.coordinator.page(for: currentPage)
uiViewController.setViewControllers([page], direction: direction, animated: true)
}
func makeCoordinator() -> Coordinator {
return Coordinator(self)
}
class Coordinator: NSObject, UIPageViewControllerDelegate, UIPageViewControllerDataSource {
private var parent: PagerView
init(_ parent: PagerView) {
self.parent = parent
}
func page(for index: Data.Index) -> PageViewController<Page> {
return PageViewController(rootView: parent.content(parent.data[index]), index: index)
}
func pageViewController(
_ pageViewController: UIPageViewController,
viewControllerBefore viewController: UIViewController
) -> UIViewController? {
guard parent.currentPage > parent.data.startIndex else { return nil }
return page(for: parent.data.index(parent.currentPage, offsetBy: -1))
}
func pageViewController(
_ pageViewController: UIPageViewController,
viewControllerAfter viewController: UIViewController
) -> UIViewController? {
guard parent.currentPage < parent.data.index(parent.data.endIndex, offsetBy: -1) else { return nil }
return page(for: parent.data.index(parent.currentPage, offsetBy: 1))
}
func pageViewController(
_ pageViewController: UIPageViewController,
didFinishAnimating finished: Bool,
previousViewControllers: [UIViewController],
transitionCompleted completed: Bool
) {
if completed, let viewController = pageViewController.viewControllers?.first as? PageViewController<Page> {
parent.currentPage = viewController.index
}
}
}
class PageViewController<Content: View>: UIHostingController<Content> {
var index: Data.Index
init(rootView: Content, index: Data.Index) {
self.index = index
super.init(rootView: rootView)
}
@MainActor @objc required dynamic init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .clear
}
}
}
最佳答案
我看到您嵌入了一个 UIHostingController
。我发现将其作为 subview 会导致导航栏重新出现,因为在某些情况下它会将 hidden 设置为 false(不确定何时)。
尝试 this answer 中的方法,从您的 UIHostingController
中删除对 UINavigationController
的访问:
class PageViewController<Content: View>: UIHostingController<Content> {
public override var navigationController: UINavigationController? {
nil
}
...
}
(这确实是 Apple 应该解决的问题。目前 UIHostingController
在嵌入到 SwiftUI View 层次结构中时并不能很好地发挥作用。)
关于ios - UIPageViewController 滑动忽略 SwiftUI 的 navigationBarHidden(true),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/69883830/