SwiftUi 3.0 - @EnvironmentObject causing NavigationLink to pop

Question

I've encountered a very odd bug in one of my apps on iOS 15 / SwiftUi 3.0 - can't find any info on it.

I have a series of 3 screens that each link to one another with a tag/selection NavigationLink as below:

NavigationLink(destination: CityListView(city: city, selection: $citySelection, orgId: self.orgId), tag: city.id, selection: $citySelection) {
                CityRow(city: city)
            }

The $citySelection is a binding on each subsequent view to allow the app to programmatically pop the views back to the first when needed.

However, since iOS 15 there is a very odd behaviour when the app is brought foward from the background. Essentially all the views pop back to the first view. Even if I remove all the above bindings it still happens and it seems to be related to one of my @EnvironmentObject.

Each of these views has access to @EnvironmentObject NotificationHandler - notifcation handler is called from many places in the app to let the users know something is happening - background processing / api calls etc. Its very simple - code below:

class NotificationHandler: ObservableObject {

// Boot Notification Center
let nc = NotificationCenter.default

@Published var networkActive: Bool = false

init() {
    print("NOTIFICATION HANDLER BOOTED")
    nc.addObserver(self, selector: #selector(networkStart), name: Notification.Name("networkingStart"), object: nil)
    nc.addObserver(self, selector: #selector(networkStop), name: Notification.Name("networkingStop"), object: nil)
}

@objc private func networkStart() {
    self.networkActive = true
}


@objc private func networkStop() {
    self.networkActive = false  
}

}

Each of my three screens accesses the networkActive variable to decide if it needs to show a progress bar:

if self.notificationHandler.networkActive {
                ProgressBar()
                Spacer()
          }

The problem is, when the app comes back from the background, if the notificationHandler is used at all, the app pops all the screens back to the first one.

If I remove the @EnvironmentObject form the first NavigationLink view this behaviour stops but I obviously can't use the progress bar without it. Accessing the @EnvironmentObject on any of the other views does not cause this behaviour, only the first.

Additionally, this behaviour doesn't happen on iOS 14.5

Any thoughts would be greatly appretiated.

Thanks

SwiftUi 3.0 - @EnvironmentObject causing NavigationLink to pop

0 Answers