SwiftUI:检测 NavigationView 后退按钮按下 [英] SwiftUI: detecting the NavigationView back button press

问题描述

在 SwiftUI 中，当我在此代码中的 DetailView1 中时，我找不到检测用户何时点击导航视图的默认后退按钮的方法:

In SwiftUI I couldn't find a way to detect when the user taps on the default back button of the navigation view when I am inside DetailView1 in this code:

struct RootView: View {
    @State private var showDetails: Bool = false
    var body: some View {
        NavigationView {
            VStack {
                NavigationLink(destination: DetailView1(), isActive: $showDetails) {
                    Text("show DetailView1")
                }
            }
            .navigationBarTitle("RootView")
        }
    }
}

struct DetailView1: View {
    @State private var showDetails: Bool = false
    var body: some View {
        NavigationLink(destination: DetailView2(), isActive: $showDetails) {
            Text("show DetailView2")
        }
        .navigationBarTitle("DetailView1")
    }
}

struct DetailView2: View {
    var body: some View {
        Text("")
            .navigationBarTitle("DetailView2")
    }
}

使用 .onDisappear 不能解决问题，因为它的闭包在视图弹出或新视图被推送时被调用.

Using .onDisappear doesn't solve the problem as its closure is called when the view is popped off or a new view is pushed.

推荐答案

观察已发布的 showDetails 属性的更好(SwiftUI-ier?)方式:

An even nicer (SwiftUI-ier?) way of observing the published showDetails property:

struct RootView: View {
    class ViewModel: ObservableObject {
        @Published var showDetails = false
    }
    @ObservedObject var viewModel = ViewModel()

    var body: some View {
        NavigationView {
            VStack {
                NavigationLink(destination: DetailView1(), isActive: $viewModel.showDetails) {
                    Text("show DetailView1")
                }
            }
            .navigationBarTitle("RootView")
            .onReceive(self.viewModel.$showDetails) { isShowing in
                debugPrint(isShowing)
                // Maybe do something here?
            }
        }
    }
}

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