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ios - 如何在另一个 NavigationLink 中有一个 NavigationLink

问题描述

我和我的团队目前正在 SwiftUI 中开发一个 Mastodon 客户端，我有一个简单的 StatusView，我可以在其中显示所有帖子数据，目前看起来像这样：

示例帖子

这个视图，在我的项目中称为StatusView，有两个NavigationLinks：主要的一个，将用户重定向到帖子的线程，一个在点击帖子的个人资料图片时将用户重定向到帖子的作者个人资料。

直到这里，一切正常。如果您点击帖子上不是按钮（例如、提升和分享）或个人资料图片的任何地方，它会打开该主题。如果您点击个人资料图片，则会打开作者的个人资料。

在此处输入图像描述

但是，如果您点击个人资料图片下方，应用程序会崩溃，只会给我以下错误：

2020-08-23 21:32:39.929392-0400 Hyperspace[830:147862] WF: _WebFilterIsActive returning: NO
2020-08-23 21:32:40.117865-0400 Hyperspace[830:147862] [assertion] Error acquiring assertion: <Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}>
2020-08-23 21:32:40.117994-0400 Hyperspace[830:147862] [ProcessSuspension] 0x11decfa80 - ProcessAssertion: Failed to acquire RBS Background assertion 'WebProcess Background Assertion' for process with PID 837, error: Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}
2020-08-23 21:32:40.119401-0400 Hyperspace[830:147862] [assertion] Error acquiring assertion: <Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}>
2020-08-23 21:32:40.119549-0400 Hyperspace[830:147862] [ProcessSuspension] 0x11decfac0 - ProcessAssertion: Failed to acquire RBS Suspended assertion 'WebProcess Suspended Assertion' for process with PID 837, error: Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}
Fatal error: UIKitNavigationBridge: multiple active destinations: file SwiftUI, line 0
2020-08-23 21:32:40.292135-0400 Hyperspace[830:147862] Fatal error: UIKitNavigationBridge: multiple active destinations: file SwiftUI, line 0

我猜这是因为当您点击那里时，线程和配置文件的导航链接都被触发，导致应用程序崩溃，因为有多个活动目的地，因为它试图同时进入线程和配置文件。

TL;博士

我的应用程序崩溃了，因为两个 NavigationLink 在它们不应该被同时触发的时候被触发了。

我怎样才能解决这个问题？

提前致谢。

我的代码

/// The status is being displayed in a ``StatusList``, so we should make it smaller and more compact.
private struct CompactStatusView: View {

    /// The ``Status`` data model from where we obtain all the data.
    var status: Status

    /// Used to trigger the navectigationLink to redirect the user to the thread.
    @Binding var goToThread: Bool

    /// Used to redirect the user to a specific profile.
    @Binding var profileViewActive: Bool

    var body: some View {
        ZStack {

            self.content
                .padding(.vertical, 5)
                .contextMenu(
                    ContextMenu(menuItems: {

                        Button(action: {}, label: {
                            Label("Report post", systemImage: "flag")
                        })

                        Button(action: {}, label: {
                            Label("Report \(self.status.account.displayName)", systemImage: "flag")
                        })

                        Button(action: {}, label: {
                            Label("Share as Image", systemImage: "square.and.arrow.up")
                        })

                    })
                )

        }
            .buttonStyle(PlainButtonStyle())
            .navigationBarHidden(self.profileViewActive)
    }

    var content: some View {
        HStack(alignment: .top, spacing: 12) {

            URLImage(URL(string: self.status.account.avatarStatic)!,
                placeholder: { _ in
                    Image("amodrono")
                        .resizable()
                        .scaledToFit()
                        .clipShape(Circle())
                        .frame(width: 50, height: 50)
                        .redacted(reason: .placeholder)
                },
                content: {
                    $0.image
                        .resizable()
                        .scaledToFit()
                        .clipShape(Circle())
                        .frame(width: 50, height: 50)
                }
            )
                .onTapGesture {
                    self.profileViewActive.toggle()
                }
                .background(
                    NavigationLink(
                        destination: ProfileView(
                            accountInfo: ProfileViewModel(
                                accountID: self.status.account.id
                            ),
                            isParent: false
                        ),
                        isActive: self.$profileViewActive
                    ) {
                        Text("")
                    }
                        .frame(width: 0, height: 0)
                )

            VStack(alignment: .leading, spacing: 2) {
                HStack(alignment: .firstTextBaseline) {

                    if !self.status.account.displayName.isEmpty {
                        Text("\(self.status.account.displayName)")
                            .font(.headline)
                            .lineLimit(1)
                    }

                    Text("@\(self.status.account.acct)")
                        .foregroundColor(.secondary)
                        .lineLimit(1)

                    Text("· \(self.status.createdAt.getDate()!.getInterval())")
                        .foregroundColor(.secondary)
                        .lineLimit(1)
                }

                StatusViewContent(
                    isMain: false,
                    content: self.status.content,
                    card: self.status.card,
                    attachments: self.status.mediaAttachments,
                    goToProfile: self.$profileViewActive
                )

                StatusActionButtons(
                    isMain: false,
                    repliesCount: self.status.repliesCount,
                    reblogsCount: self.status.reblogsCount,
                    favouritesCount: self.status.favouritesCount,
                    statusUrl: self.status.uri
                )

            }
                .onTapGesture {
                    self.goToThread.toggle()
                }
                .background(
                    NavigationLink(
                        destination: ThreadView(
                            mainStatus: self.status
                        ),
                        isActive: self.$goToThread
                    ) {
                        EmptyView()
                    }
                )

            Spacer()
        }
    }

}

我想这里的重要部分是：

个人资料图片：

URLImage(URL(string: self.status.account.avatarStatic)!,
                placeholder: { _ in
                    Image("amodrono")
                        .resizable()
                        .scaledToFit()
                        .clipShape(Circle())
                        .frame(width: 50, height: 50)
                        .redacted(reason: .placeholder)
                },
                content: {
                    $0.image
                        .resizable()
                        .scaledToFit()
                        .clipShape(Circle())
                        .frame(width: 50, height: 50)
                }
            )
                .onTapGesture {
                    self.profileViewActive.toggle()
                }
                .background(
                    NavigationLink(
                        destination: ProfileView(
                            accountInfo: ProfileViewModel(
                                accountID: self.status.account.id
                            ),
                            isParent: false
                        ),
                        isActive: self.$profileViewActive
                    ) {
                        Text("")
                    }
                        .frame(width: 0, height: 0)
                )

最后两个修饰符

.onTapGesture {
                    self.goToThread.toggle()
                }
                .background(
                    NavigationLink(
                        destination: ThreadView(
                            mainStatus: self.status
                        ),
                        isActive: self.$goToThread
                    ) {
                        EmptyView()
                    }
                )

标签： iosswiftuiuikitswiftui-navigationlink

解决方案

这是一些复制场景的可能解决方案的演示（因为提供的代码不能按原样测试）。这个想法是重用一个 NavigationLink 但根据激活位置的不同目的地。

使用 Xcode 12 / iOS 14 测试

struct DemoRowView: View {
    @State private var isProfile = false
    @State private var isActive = false
    var body: some View {
        HStack {
            Image(systemName: "person")
                .scaledToFit()
                .onTapGesture {
                    self.isProfile = true
                    self.isActive = true
                }
            Text("Thread description")
                .onTapGesture {
                    self.isProfile = false
                    self.isActive = true
                }
                .background(
                    NavigationLink(destination: self.destination(), isActive: $isActive) { EmptyView() }
                )
        }
        .buttonStyle(PlainButtonStyle())
    }

    @ViewBuilder
    private func destination() -> some View {
        if isProfile {
            ProfileView()
        } else {
            ThreadView()
        }
    }
}

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