wwt / SwiftCurrent

A library for managing complex workflows in Swift
https://wwt.github.io/SwiftCurrent/
Apache License 2.0
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[Bug]: Navigation seems to only work once #220

Open Tyler-Keith-Thompson opened 1 year ago

Tyler-Keith-Thompson commented 1 year ago

What happened?

I think this is entirely related to a known SwiftUI bug and the deprecation of NavLinks with isActive bindings. Effectively, isActive never gets set to false. You can confirm this by adding an onChange modifier and pressing the built in "back" button. Because it never gets set to false, setting it to true triggers no changes.

Version

iOS 16

Relevant code sample

// Here's a reproducible example:

import SwiftUI
import Combine

struct ContentView: View {
    var body: some View {
        NavigationStack {
            VStack {
                Combiner(current: Screen1(), next: Combiner(current: Screen2(), next: Combiner(current: Screen3())))
            }
        }
        .padding()
    }
}

protocol FlowRepresentableView: View { }

extension Never: FlowRepresentableView { }

class Workflow: ObservableObject {
    let proceedPublisher = PassthroughSubject<Void, Never>()
}

struct Combiner<Current: FlowRepresentableView, Next: FlowRepresentableView>: FlowRepresentableView {
    @State var current: Current
    @State var next: Next?
    @State var isActive: Bool = false
    @StateObject var workflow = Workflow()

    init(current: Current, next: Next) {
        _current = State(wrappedValue: current)
        _next = State(wrappedValue: next)
    }

    init(current: Current) where Next == Never {
        _current = State(wrappedValue: current)
        _next = State(wrappedValue: nil)
    }

    var body: some View {
        Group {
            if let next {
                NavigationLink(destination: next, isActive: $isActive) { }
                    .isDetailLink(false)
            }
            current
        }
        .onReceive(workflow.proceedPublisher) {
            isActive = true
        }
        .environmentObject(workflow)
    }
}

struct Screen1: FlowRepresentableView {
    @EnvironmentObject var workflow: Workflow
    var body: some View {
        Text("\(String(describing: Self.self))")
            .onTapGesture {
                workflow.proceedPublisher.send()
            }
    }
}

struct Screen2: FlowRepresentableView {
    @EnvironmentObject var workflow: Workflow
    var body: some View {
        Text("\(String(describing: Self.self))")
            .onTapGesture {
                workflow.proceedPublisher.send()
            }
    }
}

struct Screen3: FlowRepresentableView {
    @EnvironmentObject var workflow: Workflow
    var body: some View {
        Text("\(String(describing: Self.self))")
            .onTapGesture {
                workflow.proceedPublisher.send()
            }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Relevant log output

No response

Code of Conduct

Tyler-Keith-Thompson commented 1 year ago

Note: Using the new:

        .navigationDestination(isPresented: $isActive, destination: {
            next
        })

syntax does work.