Question

我有一个TabView和每个Tab项目单独的NavigationView堆栈。它工作正常，但是当我打开任何NavigationLink时，仍会显示TabView栏。我希望它在我单击任何NavigationLink时都消失。

struct MainView: View {
    @State private var tabSelection = 0

    var body: some View {
        TabView(selection: $tabSelection) {
            FirstView()
                .tabItem {
                    Text("1")
                }
                .tag(0)
            SecondView()
                .tabItem {
                    Text("2")
                }
                .tag(1)
        }
    }
}

struct FirstView: View {
    var body: some View {
        NavigationView {
            NavigationLink(destination: FirstChildView()) { // How can I open FirstViewChild with the TabView bar hidden?
                Text("Go to...")
            }
            .navigationBarTitle("FirstTitle", displayMode: .inline)
        }
    }
}

我找到了一种将TabView放在NavigationView内的解决方案，因此，在单击NavigationLink之后，TabView栏被隐藏了。但这搞乱了Tab项目的NavigationBarTitles。

struct MainView: View {
    @State private var tabSelection = 0

    var body: some View {
        NavigationView {
            TabView(selection: $tabSelection) {
                ...
            }
        }
    }
}

struct FirstView: View {
    var body: some View {
        NavigationView {
            NavigationLink(destination: FirstChildView()) {
                Text("Go to...")
            }
            .navigationBarTitle("FirstTitle", displayMode: .inline) // This will not work now
        }
    }
}

使用此解决方案，每个TabView项具有不同的NavigationTabBar的唯一方法是使用嵌套的NavigationViews。也许有一种方法可以正确实现嵌套的NavigationViews？（据我所知，导航层次结构中应该只有一个NavigationView。）

如何在SwiftUI中正确隐藏NavigationLink视图中的TabView栏？

Answer 1

可能的解决方法可以基于我对Programmatically detect Tab Bar or TabView height in SwiftUI的回答中的TabBarAccessor

这是保留NavigationView的选项卡项中的必需修改。使用Xcode 11.4 / iOS 13.4进行了测试

struct FirstTabView: View {
    @State private var tabBar: UITabBar! = nil

    var body: some View {
        NavigationView {
            NavigationLink(destination:
                FirstChildView()
                    .onAppear { self.tabBar.isHidden = true }     // !!
                    .onDisappear { self.tabBar.isHidden = false } // !!
            ) {
                Text("Go to...")
            }
            .navigationBarTitle("FirstTitle", displayMode: .inline)
        }
        .background(TabBarAccessor { tabbar in   // << here !!
            self.tabBar = tabbar
        })
    }
}

注意：或者当然，如果FirstTabView应该是可重用的并且可以独立实例化，则应该将tabBar内部的属性设置为可选，并明确处理不存在的tabBar。

Answer 2

多亏了另一个Asperi的answer，我才找到了一种不会破坏动画并且看上去自然的解决方案。

struct ContentView: View {
    @State private var tabSelection = 1

    var body: some View {
        NavigationView {
            TabView(selection: $tabSelection) {
                FirstView()
                    .tabItem {
                        Text("1")
                    }
                    .tag(1)
                SecondView()
                    .tabItem {
                        Text("2")
                    }
                    .tag(2)
            }
            // global, for all child views
            .navigationBarTitle(Text(navigationBarTitle), displayMode: .inline)
            .navigationBarHidden(navigationBarHidden)
            .navigationBarItems(leading: navigationBarLeadingItems, trailing: navigationBarTrailingItems)
        }
    }
}

struct FirstView: View {
    var body: some View {
        NavigationLink(destination: Text("Some detail link")) {
            Text("Go to...")
        }
    }
}

struct SecondView: View {
    var body: some View {
        Text("We are in the SecondView")
    }
}

动态计算navigationBarTitle和navigationBarItems：

private extension ContentView {
    var navigationBarTitle: String {
        tabSelection == 1 ? "FirstView" : "SecondView"
    }
    
    var navigationBarHidden: Bool {
        tabSelection == 3
    }

    @ViewBuilder
    var navigationBarLeadingItems: some View {
        if tabSelection == 1 {
            Text("+")
        }
    }

    @ViewBuilder
    var navigationBarTrailingItems: some View {
        if tabSelection == 1 {
            Text("-")
        }
    }
}

Answer 3

我真的很喜欢上面发布的解决方案，但是我不喜欢TabBar不会根据视图转换隐藏的事实。实际上，当使用tabBar.isHidden时向左滑动以向后导航时，结果是不可接受的。

我决定放弃原生SwiftUI TabView并编写自己的代码。结果在用户界面中更加美观：

以下是用于获得此结果的代码：

首先，定义一些视图：

struct FirstView: View {
    var body: some View {
        NavigationView {
            VStack {
                Text("First View")
                    .font(.headline)
            }
            .navigationTitle("First title")
            .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
            .background(Color.yellow)
        }
    }
}

struct SecondView: View {
    var body: some View {
        VStack {
            NavigationLink(destination: ThirdView()) {
                Text("Second View, tap to navigate")
                    .font(.headline)
            }
        }
        .navigationTitle("Second title")
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
        .background(Color.orange)
    }
}

struct ThirdView: View {
    var body: some View {
        VStack {
            Text("Third View with tabBar hidden")
                .font(.headline)
        }
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
        .background(Color.red.edgesIgnoringSafeArea(.bottom))
    }
}

然后，创建TabBarView（它将是您的应用程序中使用的根视图）：

struct TabBarView: View {
    enum Tab: Int {
        case first, second
    }
    
    @State private var selectedTab = Tab.first
    
    var body: some View {
        VStack(spacing: 0) {
            ZStack {
                if selectedTab == .first {
                    FirstView()
                }
                else if selectedTab == .second {
                    NavigationView {
                        VStack(spacing: 0) {
                            SecondView()
                            tabBarView
                        }
                    }
                }
            }
            .animation(nil)
            
            if selectedTab != .second {
                tabBarView
            }
        }
    }
    
    var tabBarView: some View {
        VStack(spacing: 0) {
            Divider()
            
            HStack(spacing: 20) {
                tabBarItem(.first, title: "First", icon: "hare", selectedIcon: "hare.fill")
                tabBarItem(.second, title: "Second", icon: "tortoise", selectedIcon: "tortoise.fill")
            }
            .padding(.top, 8)
        }
        .frame(height: 50)
        .background(Color.white.edgesIgnoringSafeArea(.all))
    }
    
    func tabBarItem(_ tab: Tab, title: String, icon: String, selectedIcon: String) -> some View {
        ZStack(alignment: .topTrailing) {
            VStack(spacing: 3) {
                VStack {
                    Image(systemName: (selectedTab == tab ? selectedIcon : icon))
                        .font(.system(size: 24))
                        .foregroundColor(selectedTab == tab ? .primary : .black)
                }
                .frame(width: 55, height: 28)
                
                Text(title)
                    .font(.system(size: 11))
                    .foregroundColor(selectedTab == tab ? .primary : .black)
            }
        }
        .frame(width: 65, height: 42)
        .onTapGesture {
            selectedTab = tab
        }
    }
}

此解决方案还允许在TabBar中进行很多自定义。例如，您可以添加一些通知徽章。

Answer 4

怎么样，

struct TabSelectionView: View {
    @State private var currentTab: Tab = .Scan
    
    private enum Tab: String {
        case Scan, Validate, Settings
    }
    
    var body: some View {
        TabView(selection: $currentTab){
            
            ScanView()
                .tabItem {
                    Label(Tab.Scan.rawValue, systemImage: "square.and.pencil")
                }
                .tag(Tab.Scan)
            
            ValidateView()
                .tabItem {
                    Label(Tab.Validate.rawValue, systemImage: "list.dash")
                }
                .tag(Tab.Validate)
            
            SettingsView()
                .tabItem {
                    Label(Tab.Settings.rawValue, systemImage: "list.dash")
                }
                .tag(Tab.Settings)
        }
        .navigationBarTitle(Text(currentTab.rawValue), displayMode: .inline)
    }
}

SwiftUI在NavigationLink视图内隐藏TabView栏

4 个答案: