Flickering effect when showing a nested view

[rojarand]

I came across strange flickering effect when creating a nested view stack with Helm. It looks like the child view is being open twice. For demonstration purpose I added a nested view to the Navigation example. Additionally there is an infinite transition loop between the most nested views. The gif below shows the issue.

The view with text "Chelsea FC has a lot of supporters" flickers. The "Club Details View" can not be accessed because it is being closed just right after opening that view.

I tested all combinations of dismissable and hold/pass properties. Without a success.

Changes needed to recreate the issue:

• ContentView.swift

struct ContentView: View {
    var body: some View {
        NavigationEntryView()
    }
}

• NavigationEntryView.swift

struct NavigationEntryView: View {
    @StateObject private var _helm: Helm = try! Helm(nav: [
        SampleSegue(.a => .b).with(style: .hold),
        SampleSegue(.b => .c).with(style: .hold),
        SampleSegue(.c => .d).with(style: .hold),
    ])
    
    var body: some View {
        NavigationExampleView()
            .environmentObject(_helm)
    }
}

• NavigationExampleView.swift

struct NavigationExampleView: View {
    @EnvironmentObject private var _helm: Helm<SampleFragment>
    
    var body: some View {
        NavigationView {
            List {
                Section(
                    content: {
                        ForEach(["Porto", "London", "Barcelona"]) { city in
                            NavigationLink(destination: CityContentView(city: city),
                                           isActive: _helm.isPresented(.b, id: city)) {
                                Text(city)
                            }
                        }
                        Button(action: { _helm.present(fragment: .b, id: "London") }) {
                            Text("Select London")
                        }
                    },
                    footer: {
                        if let error = _helm.errors.last {
                            Section {
                                Text("Error: \(error.localizedDescription)")
                                    .foregroundColor(.red)
                            }
                        }
                    }
                )
            }
        }
    }
}

let clubsInCities: [String: [String]] = [
    "Porto": ["FC Porto", "Boavista F.C.‎"],
    "London": ["Chelsea FC", "‎Tottenham Hotspur", "West Ham", "Arsenal"],
    "Barcelona": ["FC Barcelona", "RCD Espanyol‎‎"]
]

struct CityContentView: View {
    @EnvironmentObject private var _helm: Helm<SampleFragment>
    
    let city: String
    var body: some View {
        List(clubsInCities[city] ?? []) { club in
            NavigationLink(destination: ClubContentView(club: club),
                           isActive: _helm.isPresented(.c, id: club)) {
                Text(club)
            }
        }
    }
}

struct ClubContentView: View {
    
    @EnvironmentObject private var _helm: Helm<SampleFragment>
    
    let club: String
    var body: some View {
        NavigationLink(destination: ClubDetailsContentView(club: club),
                       isActive: _helm.isPresented(.d, id: club)) {
            Text("\(club) has a lot of supporters")
        }
    }
}

struct ClubDetailsContentView: View {
    
    let club: String
    var body: some View {
        Text("Details of \(club)")
    }
}

struct NavigationView_Previews: PreviewProvider {
    static var previews: some View {
        NavigationExampleView()
    }
}

Tested with:

• Xcode: 14.1
• iOS: 15, 16
• Helm: 0.0.12-beta