SwiftUI:再次点击所选选项卡时弹出到根视图 [英] SwiftUI: Pop to root view when selected tab is tapped again

问题描述

起点是 TabView 中的 NavigationView.当再次点击所选选项卡时，我正在努力寻找 SwiftUI 解决方案以弹出导航堆栈中的根视图.在 SwiftUI 之前，这很简单:

Starting point is a NavigationView within a TabView. I'm struggling with finding a SwiftUI solution to pop to the root view within the navigation stack when the selected tab is tapped again. In the pre-SwiftUI times, this was as simple as the following:

func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
    let navController = viewController as! UINavigationController
    navController.popViewController(animated: true)
}

您知道如何在 SwiftUI 中实现相同的功能吗?

Do you know how the same thing can be achieved in SwiftUI?

目前，我使用以下依赖于 UIKit 的解决方法:

Currently, I use the following workaround that relies on UIKit:

if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)

            let navigationController = UINavigationController(rootViewController: UIHostingController(rootView:
                MyCustomView() // -> this is a normal SwiftUI file
                    .environment(\.managedObjectContext, context)
            ))
            navigationController.tabBarItem = UITabBarItem(title: "My View 1", image: nil, selectedImage: nil)

            // add more controllers that are part of tab bar controller

            let tabBarController = UITabBarController()
            tabBarController.viewControllers = [navigationController /*,  additional controllers */]

            window.rootViewController = tabBarController // UIHostingController(rootView: contentView)
            self.window = window
            window.makeKeyAndVisible()
        }

推荐答案

这里是可能的方法.对于 TabView，它提供与点击另一个选项卡并返回相同的行为，因此提供持久的外观和感觉.

Here is possible approach. For TabView it gives the same behaviour as tapping to the another tab and back, so gives persistent look & feel.

经过测试适用于 Xcode 11.2/iOS 13.2

Tested & works with Xcode 11.2 / iOS 13.2

完整模块代码:

import SwiftUI

struct TestPopToRootInTab: View {
    @State private var selection = 0
    @State private var resetNavigationID = UUID()

    var body: some View {

        let selectable = Binding(        // << proxy binding to catch tab tap
            get: { self.selection },
            set: { self.selection = $0

                // set new ID to recreate NavigationView, so put it
                // in root state, same as is on change tab and back
                self.resetNavigationID = UUID()
        })

        return TabView(selection: selectable) {
            self.tab1()
                .tabItem {
                    Image(systemName: "1.circle")
                }.tag(0)
            self.tab2()
                .tabItem {
                    Image(systemName: "2.circle")
                }.tag(1)
        }
    }

    private func tab1() -> some View {
        NavigationView {
            NavigationLink(destination: TabChildView()) {
                Text("Tab1 - Initial")
            }
        }.id(self.resetNavigationID) // << making id modifiable
    }

    private func tab2() -> some View {
        Text("Tab2")
    }
}

struct TabChildView: View {
    var number = 1
    var body: some View {
        NavigationLink("Child \(number)",
            destination: TabChildView(number: number + 1))
    }
}

struct TestPopToRootInTab_Previews: PreviewProvider {
    static var previews: some View {
        TestPopToRootInTab()
    }
}

这篇关于SwiftUI:再次点击所选选项卡时弹出到根视图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！