How does SwiftUI pass EnvironmentObjects between HostingController?

Question

I am trying to implement an Apple Watch app in a similar way as this question: Issues implementing navigation from a main controller to page based controllers in WatchOS using SwiftUI

I am trying to pass data between different HostingControllers. My data is stored in an EnvironmentObject with published properties. If I only use one HostingController, it's fine to share data between the different views. But when using a different HostingController, hosting different views (without segues), I can't find the syntax for using my Environment object from HC1 to HC2, the HC3, etc.

I present the HostingController using this piece of code in my SwiftUI views.

NavigationLink(destinationName: "HC2"){
        Text("Go to HC2")

What approach did you go for in the end? I'm facing the exact same issue. — bencallis, May 16 '20 at 21:10
I have used this approach which fits my needs. But now, I have another issue. I don't know how to go back to the first HostingController from HC3 or HC4 — Raphaël Barthomeuf, May 18 '20 at 06:02
@bencallis, did you ever find a workable solution for this? I have multiple UIHostingControllers in a navigationcontroller that I want to share data between. — spentag, May 26 '21 at 23:27

score 3 · Accepted Answer · edited Aug 23 '22 at 14:58

Here is possible approach

class AppState: ObservableObject {
    static let shared = AppState()      // shared instance

    @Published var setting: String = "some"
}

class HostingController: WKHostingController<AnyView> {
    override var body: AnyView {
        let contentView = ContentView()
            .environmentObject(AppState.shared)     // << inject !!
        return AnyView(contentView)
    }
}

class HostingController2: WKHostingController<AnyView> {
    override var body: AnyView {
        let contentView = ContentView2()
            .environmentObject(AppState.shared)     // << inject !!
        return AnyView(contentView)
    }
}

Are there any other approaches? Resorting to using global shared data really doesn't seem ideal. — bencallis, May 16 '20 at 21:10

How does SwiftUI pass EnvironmentObjects between HostingController?

1 Answers1