Why does modifying the label of a NavigationLink change which View is displayed in SwiftUI?

user_13603858 0
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I have an @EnvironmentObject called word (of type Word) whose identifier property I'm using for the label of a NavigationLink in SwiftUI. For the DetailView that is linked to the NavigationLink, all I have put is this:

struct DetailView: View {
    @EnvironmentObject var word: Word

    var body: some View {
        VStack {
            Text(word.identifier)
            Button(action: {
                self.word.identifier += "a"
            }) {
                Text("Click to add an 'a' to Word's identifier")
            }
        }
    }
}

The ContentView that leads to this DetailView looks like this (I've simplified my actual code to isolate the problem).

struct ContentView: View {

    @EnvironmentObject var word: Word

    var body: some View {
        NavigationView {
            NavigationLink(destination: DetailView()) {
                Text(word.identifier)
            }
        }
    }
}

When I tap the button on the DetailView, I'd expect it to update the DetailView with a new word.identifier that has an extra "a" appended onto it. When I tap it, however, it takes me back to the ContentView, albeit with an updated word.identifier. I can't seem to find a way to stay on my DetailView when the word.identifier being used by the ContentView's NavigationLink is modified. Also, I am running Xcode 11.3.1 and am currently unable to update, so if this is has been patched, please let me know.

xcode11 swiftui-navigationlink swiftui swift xcode
2 Answers

Here is workaround solution

struct DetailView: View {
    @EnvironmentObject var word: Word

    @State private var identifier: String = ""

    var body: some View {
        VStack {
            Text(self.identifier)
            Button(action: {
                self.identifier += "a"
            }) {
                Text("Click to add an 'a' to Word's identifier")
            }
        }
        .onAppear {
           self.identifier = self.word.identifier
        }
        .onDisappear {
           self.word.identifier = self.identifier
        }
    }
}
user_122990300

This works as expected on iOS 13.4, assuming Word is something like:

class Word : ObservableObject {
    @Published var identifier = "foo"
}
user_1280830
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