如何检测返回到 SwiftUI 中 NavigationView 的根视图?

问题描述

我看到ContentView出现了！"消息仅第一次/onAppear 似乎被称为

I see "ContentView appeared!" message only first time/ onAppear seems to be called ones

是否可以通过其他方式检测回根?

Is it possible to detect return to the root in any other way?

import SwiftUI

struct ContentView: View {
    var body: some View {
        NavigationView {
            VStack {
                NavigationLink(destination: DetailView()) {
                    Text("Hello World")
                }
            }
        }.onAppear {
            print("ContentView appeared!")
        }.onDisappear {
            print("ContentView disappeared!")
        }
    }
}

struct DetailView: View {
    var body: some View {
        VStack {
            Text("Second View")
        }.onAppear {
                print("DetailView appeared!")
        }.onDisappear {
                print("DetailView disappeared!")
        }
    }
}

推荐答案

NavigationView 在 view 之间持久化.所以当你在它们之间推送和弹出时，它实际上不是 appear 和 disappear .所以你需要在 NavigationView 的内容上设置 modifiers，NOT NavigationView 它自己:

NavigationView is persist between views. So it's not actually appear and disappear when you push and pop between them. So you need to set the modifiers on the NavigationView's content, NOT the NavigationView it self:

NavigationView {
    NavigationLink(destination: DetailView()) { Text("Hello World") }

    .onAppear { print("ContentView appeared!") }
    .onDisappear { print("ContentView disappeared!") }
}

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