Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '<SwiftUI.UIKitNavigationController: 0x10282e200> is pushing the same view controller instance

[nick-maker]

If I navigate to a second view (sometimes stop at the first view), it will crash if I tap the back button to the first view and navigate to any other second view.

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '<SwiftUI.UIKitNavigationController: 0x10282e200> is pushing the same view controller instance (<TtGC7SwiftUI32NavigationStackHostingControllerVS_7AnyView: 0x105828800>) more than once which is not supported and is most likely an error in the application : com.rblabs.popopoint'
*** First throw call stack:
(0x1a5bdfb28 0x19da42f78 0x1a7e431cc 0x1a7e422e0 0x1ab24a14c 0x1ab2527ec 0x1ab23dd8c 0x1ab2478bc 0x1ab243408 0x1aa965adc 0x1ab06b620 0x1ab06b070 0x1ab0691b8 0x1ab0d91ac 0x1ab0d920c 0x1a7daa8bc 0x1a71d5d5c 0x1a71d58e0 0x1a71dbae0 0x1a71d50e8 0x1a71d4d90 0x1a7e22bfc 0x1a7e22714 0x1a7e21e04 0x1a7e21ec0 0x1a5b2a62c 0x1a5b298a8 0x1a5b28058 0x1a5b26d88 0x1a5b26968 0x1ea23b4e0 0x1a7fa3350 0x1a7fa298c 0x1aa96ba28 0x1aa96b870 0x1aa587bc4 0x1007d5470 0x1007d5520 0x1c946ad84)
libc++abi: terminating due to uncaught exception of type NSException

Code

HomeDetailModel.swift

import SwiftUI
import SwiftUINavigation

class HomeDetailModel: ObservableObject {

  init(destination: Destination? = nil, isLogin: Bool = false) {
    self.destination = destination
    self.isLogin = isLogin
  }

  enum Destination {
    case invitation
    case setting
    case bindPhone(ProfileDetailModel)
    case profile(ProfileDetailModel)
  }

  @Published var destination: Destination?

  @Published var isLogin: Bool

  func didReceiveUserInfo() {
    destination = nil
    DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
      self.destination = .invitation
    }
  }

  @MainActor
  func profileButtonTapped() {
    destination = .profile(ProfileDetailModel())
  }

  @MainActor
  func skipButtonTapped() async {
    isLogin = true // TODO: change from overlay to full screen cover
    try? await Task.sleep(for: .seconds(0.3))
    destination = .bindPhone(ProfileDetailModel())
  }

  @MainActor
  func bindPhoneButtonTapped() async {
    print(1)
    try? await Task.sleep(for: .seconds(0.3))
    print(2)
    destination = .profile(ProfileDetailModel(destination: .setting))
    print(3)
  }

}

extension HomeDetailModel: @unchecked Sendable { }

HomeView

import SwiftUI
import SwiftUINavigation

struct HomeView: View {

  @ObservedObject var model: HomeDetailModel

  var body: some View {
    NavigationStack {
      ScrollView(.vertical, showsIndicators: false) {
        allCardsView()
        Spacer(minLength: .ideal(70) * CGFloat(model.memberCards.count))
      }
      .navigationDestination(
        unwrapping: $model.destination,
        case: /HomeDetailModel.Destination.profile)
      { $model in
        ProfileView(model: model)
      }
      .sheet(unwrapping: $model.destination, case: /HomeDetailModel.Destination.bindPhone) { _ in
        BindPhoneView() {
          Task {
            await model.bindPhoneButtonTapped()
          }
        }
        .presentationDetents([.height(.ideal(415))])
        .presentationDragIndicator(.visible)
      }
    }
    .overlay {
      if !model.isLogin {
        NavigationStack {
          LoginView(model: model)
        }
      }
    }
  }
}

BindPhoneView

import SwiftUI

struct BindPhoneView: View {

  @Environment(\.dismiss) var dismiss

  var onTap: () -> Void

  var body: some View {
      Button {
        dismiss()
        onTap()
      } label: {
        ButtonLabel(title: "Bind", width: 106)
      }
  }
}

Sum up

When I am in BindPhoneView, I first tap the button to dismiss the sheet and use the closure to call HomeDetailModel's method bindPhoneButtonTapped to go to the SettingView, which is one of the destinations of ProfileView. And when tapped back to ProfileView, if I call a method from ProfileDetailModel to set the destination to SettingView or any other destination, it will crash.

Demo

pomo-app-ios.zip

[mbrandonw]

Hi @nick-maker, the code you posted above does not compile. It is missing ProfileDetailModel, allCardsView, ProfileView, LoginView, ButtonLabel. It's hard to know what is going on without something to run ourselves. Ideally you would provide a minimal project that reproduces the problem you are seeing.

However, even without running the code I can tell you that 99.9% of the time this is just a limitation of vanilla SwiftUI navigation. Our tools do not really add much on top of what SwiftUI gives us. It's just some simple binding transformation helpers. So I feel confident saying that you would be able to reproduce this problem even without using our library.

[nick-maker]

Hi @mbrandonw, thank you for your prompt reply. I have uploaded a minimal demo, however, the problem has slightly changed. It doesn't go to SettingView anymore, it goes to a blank view. I think the problem is because of asynchronous, if I change it to synchronous, it will stop at ProfileView. I am guessing that I need to integrate NavigationPath so that I can navigate to a nested view or pop to the rootView.

Do you have any recommendations on this issue? Thank you.

[mbrandonw]

Hi @nick-maker, thanks for the project. That helps a lot to see what is going on.

Unfortunately you are just doing something too advanced for SwiftUI to handle. By doing this:

destination = .profile(ProfileDetailModel(destination: .setting(SettingDetailModel())))

…all in one line you are simultaneously dismissing a sheet and pushing two views onto the navigation stack. SwiftUI is just not capable of doing things like that (at least not with navigationDestination), even in vanilla SwiftUI without using our library.

If you want to keep your domain modeled exactly as you have it now, then one potential fix is to space out the destination mutations a bit. You can first nil out the destination to dismiss the sheet, then mutate destination to push the profile, and then mutate again to push the settings, all separated by some small sleeps:

@MainActor
func bindPhoneButtonTapped() async {
  destination = nil

  try? await Task.sleep(for: .seconds(0.6))
  let profileModel = ProfileDetailModel()
  destination = .profile(profileModel)

  try? await Task.sleep(for: .seconds(0.6))
  profileModel.destination = .setting(SettingDetailModel())
}

However, if you want the most bug-free way of doing these kinds of complex navigation patterns I think you should use the NavigationStack that takes a binding. It is capable of pushing multiple screens on at once without spacing things apart.

[nick-maker]

Thank you very much!